1
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Song Y, Hu Y, Zhu X, Yang K, Lončar M. Octave-spanning Kerr soliton frequency combs in dispersion- and dissipation-engineered lithium niobate microresonators. LIGHT, SCIENCE & APPLICATIONS 2024; 13:225. [PMID: 39223111 PMCID: PMC11369083 DOI: 10.1038/s41377-024-01546-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Revised: 07/18/2024] [Accepted: 07/21/2024] [Indexed: 09/04/2024]
Abstract
Dissipative Kerr solitons from optical microresonators, commonly referred to as soliton microcombs, have been developed for a broad range of applications, including precision measurement, optical frequency synthesis, and ultra-stable microwave and millimeter wave generation, all on a chip. An important goal for microcombs is self-referencing, which requires octave-spanning bandwidths to detect and stabilize the comb carrier envelope offset frequency. Further, detection and locking of the comb spacings are often achieved using frequency division by electro-optic modulation. The thin-film lithium niobate photonic platform, with its low loss, strong second- and third-order nonlinearities, as well as large Pockels effect, is ideally suited for these tasks. However, octave-spanning soliton microcombs are challenging to demonstrate on this platform, largely complicated by strong Raman effects hindering reliable fabrication of soliton devices. Here, we demonstrate entirely connected and octave-spanning soliton microcombs on thin-film lithium niobate. With appropriate control over microresonator free spectral range and dissipation spectrum, we show that soliton-inhibiting Raman effects are suppressed, and soliton devices are fabricated with near-unity yield. Our work offers an unambiguous method for soliton generation on strongly Raman-active materials. Further, it anticipates monolithically integrated, self-referenced frequency standards in conjunction with established technologies, such as periodically poled waveguides and electro-optic modulators, on thin-film lithium niobate.
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Affiliation(s)
- Yunxiang Song
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA.
- Quantum Science and Engineering, Harvard University, Cambridge, MA, USA.
| | - Yaowen Hu
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Xinrui Zhu
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Kiyoul Yang
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA.
| | - Marko Lončar
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA.
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2
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Ludwig M, Ayhan F, Schmidt TM, Wildi T, Voumard T, Blum R, Ye Z, Lei F, Wildi F, Pepe F, Gaafar MA, Obrzud E, Grassani D, Hefti O, Karlen S, Lecomte S, Moreau F, Chazelas B, Sottile R, Torres-Company V, Brasch V, Villanueva LG, Bouchy F, Herr T. Ultraviolet astronomical spectrograph calibration with laser frequency combs from nanophotonic lithium niobate waveguides. Nat Commun 2024; 15:7614. [PMID: 39223131 PMCID: PMC11369296 DOI: 10.1038/s41467-024-51560-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Accepted: 08/12/2024] [Indexed: 09/04/2024] Open
Abstract
Astronomical precision spectroscopy underpins searches for life beyond Earth, direct observation of the expanding Universe and constraining the potential variability of physical constants on cosmological scales. Laser frequency combs can provide the required accurate and precise calibration to the astronomical spectrographs. For cosmological studies, extending the calibration with such astrocombs to the ultraviolet spectral range is desirable, however, strong material dispersion and large spectral separation from the established infrared laser oscillators have made this challenging. Here, we demonstrate astronomical spectrograph calibration with an astrocomb in the ultraviolet spectral range below 400 nm. This is accomplished via chip-integrated highly nonlinear photonics in periodically-poled, nano-fabricated lithium niobate waveguides in conjunction with a robust infrared electro-optic comb generator, as well as a chip-integrated microresonator comb. These results demonstrate a viable route towards astronomical precision spectroscopy in the ultraviolet and could contribute to unlock the full potential of next-generation ground-based and future space-based instruments.
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Affiliation(s)
- Markus Ludwig
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607, Hamburg, Germany
| | - Furkan Ayhan
- École Polytechnique Fédérale de Lausanne (EPFL), 1015, Lausanne, Switzerland
| | - Tobias M Schmidt
- Observatoire de Genève, Département d'Astronomie, Université de Genève, Chemin Pegasi 51b, 1290, Versoix, Switzerland
| | - Thibault Wildi
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607, Hamburg, Germany
| | - Thibault Voumard
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607, Hamburg, Germany
| | - Roman Blum
- Swiss Center for Electronics and Microtechnology (CSEM), 2000, Neuchâtel, Switzerland
| | - Zhichao Ye
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 41296, Gothenburg, Sweden
| | - Fuchuan Lei
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 41296, Gothenburg, Sweden
| | - François Wildi
- Observatoire de Genève, Département d'Astronomie, Université de Genève, Chemin Pegasi 51b, 1290, Versoix, Switzerland
| | - Francesco Pepe
- Observatoire de Genève, Département d'Astronomie, Université de Genève, Chemin Pegasi 51b, 1290, Versoix, Switzerland
| | - Mahmoud A Gaafar
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607, Hamburg, Germany
| | - Ewelina Obrzud
- Swiss Center for Electronics and Microtechnology (CSEM), 2000, Neuchâtel, Switzerland
| | - Davide Grassani
- Swiss Center for Electronics and Microtechnology (CSEM), 2000, Neuchâtel, Switzerland
| | - Olivia Hefti
- Swiss Center for Electronics and Microtechnology (CSEM), 2000, Neuchâtel, Switzerland
| | - Sylvain Karlen
- Swiss Center for Electronics and Microtechnology (CSEM), 2000, Neuchâtel, Switzerland
| | - Steve Lecomte
- Swiss Center for Electronics and Microtechnology (CSEM), 2000, Neuchâtel, Switzerland
| | - François Moreau
- Observatoire de Haute-Provence, CNRS, Université d'Aix-Marseille, 04870, Saint-Michel-l'Observatoire, France
| | - Bruno Chazelas
- Observatoire de Genève, Département d'Astronomie, Université de Genève, Chemin Pegasi 51b, 1290, Versoix, Switzerland
| | - Rico Sottile
- Observatoire de Haute-Provence, CNRS, Université d'Aix-Marseille, 04870, Saint-Michel-l'Observatoire, France
| | - Victor Torres-Company
- Department of Microtechnology and Nanoscience, Chalmers University of Technology, 41296, Gothenburg, Sweden
| | - Victor Brasch
- Q.ANT GmbH, Handwerkstraße 29, 70565, Stuttgart, Germany
| | - Luis G Villanueva
- École Polytechnique Fédérale de Lausanne (EPFL), 1015, Lausanne, Switzerland
| | - François Bouchy
- Observatoire de Genève, Département d'Astronomie, Université de Genève, Chemin Pegasi 51b, 1290, Versoix, Switzerland
| | - Tobias Herr
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607, Hamburg, Germany.
- Physics Department, Universität Hamburg UHH, Luruper Chaussee 149, 22607, Hamburg, Germany.
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3
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He Y, Yan X, Wu J, Liu X, Chen Y, Chen X. Cascaded multi-phonon stimulated Raman scattering near second-harmonic generation in a thin-film lithium niobate microdisk. OPTICS LETTERS 2024; 49:4863-4866. [PMID: 39207983 DOI: 10.1364/ol.533732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2024] [Accepted: 08/12/2024] [Indexed: 09/04/2024]
Abstract
High-quality microresonators can greatly enhance light-matter interactions and are excellent platforms for studying nonlinear optics. Wavelength conversion through nonlinear processes is the key to many applications of integrated optics. The stimulated Raman scattering (SRS) process can extend the emission wavelength of a laser source to a wider range. Lithium niobate (LN), as a Raman active crystalline material, has remarkable potential for wavelength conversion. Here, we demonstrate the generation of cascaded multi-phonon Raman signals near the second-harmonic generation (SHG) peak in an X-cut thin-film lithium niobate (TFLN) microdisk. Fine tuning of the specific cascaded Raman spectral lines has also been made by changing the pump wavelength. Raman lines can reach a wavelength up to about 80 nm away from the SHG signal. We realize the SFG process associated with Raman signals in the visible range as well. Our work extends the use of WGM microresonators as effective optical upconversion wavelength converters in nonlinear optical applications.
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4
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He Y, Cheng L, Wang H, Zhang Y, Meade R, Vahala K, Zhang M, Li J. Chip-scale high-performance photonic microwave oscillator. SCIENCE ADVANCES 2024; 10:eado9570. [PMID: 39141728 PMCID: PMC11323879 DOI: 10.1126/sciadv.ado9570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Accepted: 07/09/2024] [Indexed: 08/16/2024]
Abstract
Optical frequency division based on bulk or fiber optics provides unprecedented spectral purity for microwave oscillators. To extend the applications of this approach, the challenges are to develop miniaturized oscillators without trading off phase noise performance. Here, we report a chip-scale high-performance photonic microwave oscillator based on integrated electro-optical frequency division. Dual distributed-feedback lasers are co-self-injection locked to a single silicon nitride spiral resonator to provide a record-high-stability, fully on-chip optical reference. An integrated electro-optical frequency comb based on a thin-film lithium niobate phase modulator chip is leveraged to perform optical-to-microwave frequency division. The resulting integrated photonic microwave oscillator achieves a record-low phase noise for chip-scale oscillators. The results represent a major advance in high-performance, integrated photonic microwave oscillators for applications including signal processing, radar, timing, and coherent communications.
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Affiliation(s)
- Yang He
- hQphotonics Inc., 2500 E Colorado Blvd Suite 330, Pasadena CA 91107, USA
| | - Long Cheng
- hQphotonics Inc., 2500 E Colorado Blvd Suite 330, Pasadena CA 91107, USA
| | - Heming Wang
- hQphotonics Inc., 2500 E Colorado Blvd Suite 330, Pasadena CA 91107, USA
| | - Yu Zhang
- HyperLight Corporation, 1 Bow Street, Suite 420, Cambridge, MA 02138, USA
| | - Roy Meade
- HyperLight Corporation, 1 Bow Street, Suite 420, Cambridge, MA 02138, USA
| | - Kerry Vahala
- T. J. Watson Laboratory of Applied Physics, California Institute of Technology, Pasadena, CA 91125, USA
| | - Mian Zhang
- HyperLight Corporation, 1 Bow Street, Suite 420, Cambridge, MA 02138, USA
| | - Jiang Li
- hQphotonics Inc., 2500 E Colorado Blvd Suite 330, Pasadena CA 91107, USA
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5
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Cheng R, Ren X, Reimer C, Yeh M, Rosborough V, Musolf J, Johansson L, Zhang M, Yu M, Lončar M. Single-drive electro-optic frequency comb source on a photonic-wire-bonded thin-film lithium niobate platform. OPTICS LETTERS 2024; 49:3504-3507. [PMID: 38875656 DOI: 10.1364/ol.527659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2024] [Accepted: 05/26/2024] [Indexed: 06/16/2024]
Abstract
Stable pulse and flat-top frequency comb generation are an indispensable component of many photonic applications, from ranging to communications. Lithium niobate on insulator is an excellent electro-optic (EO) platform, exhibiting high modulation efficiency and low optical loss, making it a fitting candidate for pulse generation through electro-optic modulation of continuous-wave (CW) light, a commonly utilized method for generating ultrashort pulses. Here, we demonstrate an on-chip electro-optic comb generation module on thin-film lithium niobate (TFLN) consisting of a Mach-Zehnder interferometer (MZI) amplitude modulator (AM) and a cascaded phase modulator (PM) system driven by a single-electrode drive. We show that when operated in the correct regime, the lithium niobate chips can generate frequency combs with excellent spectral power flatness. In addition, we optically package one of the pulse generator chips via photonic wire bonding. The pulses generated by the photonic-wire-bonded device are compressed to 840 fs pulse duration using an optical fiber and show extremely stable operation.
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6
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Ma X, Cai Z, Zhuang C, Liu X, Zhang Z, Liu K, Cao B, He J, Yang C, Bao C, Zeng R. Integrated microcavity electric field sensors using Pound-Drever-Hall detection. Nat Commun 2024; 15:1386. [PMID: 38360758 PMCID: PMC10869830 DOI: 10.1038/s41467-024-45699-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Accepted: 01/26/2024] [Indexed: 02/17/2024] Open
Abstract
Discerning weak electric fields has important implications for cosmology, quantum technology, and identifying power system failures. Photonic integration of electric field sensors is highly desired for practical considerations and offers opportunities to improve performance by enhancing microwave and lightwave interactions. Here, we demonstrate a high-Q microcavity electric field sensor (MEFS) by leveraging the silicon chip-based thin film lithium niobate photonic integrated circuits. Using the Pound-Drever-Hall detection scheme, our MEFS achieves a detection sensitivity of 5.2 μV/(m[Formula: see text]), which surpasses previous lithium niobate electro-optical electric field sensors by nearly two orders of magnitude, and is comparable to atom-based quantum sensing approaches. Furthermore, our MEFS has a bandwidth that can be up to three orders of magnitude broader than quantum sensing approaches and measures fast electric field amplitude and phase variations in real-time. The ultra-sensitive MEFSs represent a significant step towards building electric field sensing networks and broaden the application spectrum of integrated microcavities.
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Affiliation(s)
- Xinyu Ma
- State Key Laboratory of Power Systems, Department of Electrical Engineering, Tsinghua University, Beijing, 100084, China
| | - Zhaoyu Cai
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instruments, Tsinghua University, Beijing, 100084, China
| | - Chijie Zhuang
- State Key Laboratory of Power Systems, Department of Electrical Engineering, Tsinghua University, Beijing, 100084, China.
| | - Xiangdong Liu
- State Key Laboratory of Power Systems, Department of Electrical Engineering, Tsinghua University, Beijing, 100084, China
| | - Zhecheng Zhang
- State Key Laboratory of Power Systems, Department of Electrical Engineering, Tsinghua University, Beijing, 100084, China
| | - Kewei Liu
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instruments, Tsinghua University, Beijing, 100084, China
| | - Bo Cao
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instruments, Tsinghua University, Beijing, 100084, China
| | - Jinliang He
- State Key Laboratory of Power Systems, Department of Electrical Engineering, Tsinghua University, Beijing, 100084, China
| | - Changxi Yang
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instruments, Tsinghua University, Beijing, 100084, China
| | - Chengying Bao
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instruments, Tsinghua University, Beijing, 100084, China.
| | - Rong Zeng
- State Key Laboratory of Power Systems, Department of Electrical Engineering, Tsinghua University, Beijing, 100084, China.
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7
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Lima P, Cardoso W, Pádua S. Integrated photonic circuits for contextuality tests via sequential measurements in three-level quantum systems. OPTICS EXPRESS 2024; 32:5550-5566. [PMID: 38439278 DOI: 10.1364/oe.504966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Accepted: 12/27/2023] [Indexed: 03/06/2024]
Abstract
In this paper, we present a protocol to obtain photonic circuits that can be used in the implementation of contextuality tests on qutrit systems. The use of photonic integrated circuits offers several advantages for performing this type of task. These include scalability, accuracy, robustness, high-speed and efficient quantum measurements, precise control over the phase properties of photons by using electrically driven heaters to induce a thermo-optic phase shift and resistance to noise. We relate the average values that appear in the inequalities with the probability of photon counting in the circuit outputs and present a realizable configuration for the desired device, taking into account state-dependent and state-independent contextuality tests.
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8
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Li Z, Wang RN, Lihachev G, Zhang J, Tan Z, Churaev M, Kuznetsov N, Siddharth A, Bereyhi MJ, Riemensberger J, Kippenberg TJ. High density lithium niobate photonic integrated circuits. Nat Commun 2023; 14:4856. [PMID: 37563149 PMCID: PMC10415301 DOI: 10.1038/s41467-023-40502-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2022] [Accepted: 07/26/2023] [Indexed: 08/12/2023] Open
Abstract
Photonic integrated circuits have the potential to pervade into multiple applications traditionally limited to bulk optics. Of particular interest for new applications are ferroelectrics such as Lithium Niobate, which exhibit a large Pockels effect, but are difficult to process via dry etching. Here we demonstrate that diamond-like carbon (DLC) is a superior material for the manufacturing of photonic integrated circuits based on ferroelectrics, specifically LiNbO3. Using DLC as a hard mask, we demonstrate the fabrication of deeply etched, tightly confining, low loss waveguides with losses as low as 4 dB/m. In contrast to widely employed ridge waveguides, this approach benefits from a more than one order of magnitude higher area integration density while maintaining efficient electro-optical modulation, low loss, and offering a route for efficient optical fiber interfaces. As a proof of concept, we demonstrate a III-V/LiNbO3 based laser with sub-kHz intrinsic linewidth and tuning rate of 0.7 PHz/s with excellent linearity and CMOS-compatible driving voltage. We also demonstrated a MZM modulator with a 1.73 cm length and a halfwave voltage of 1.94 V.
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Affiliation(s)
- Zihan Li
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015, Lausanne, Switzerland
- Center of Quantum Science and Engineering (EPFL), CH-1015, Lausanne, Switzerland
| | - Rui Ning Wang
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015, Lausanne, Switzerland
- Center of Quantum Science and Engineering (EPFL), CH-1015, Lausanne, Switzerland
| | - Grigory Lihachev
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015, Lausanne, Switzerland
- Center of Quantum Science and Engineering (EPFL), CH-1015, Lausanne, Switzerland
| | - Junyin Zhang
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015, Lausanne, Switzerland
- Center of Quantum Science and Engineering (EPFL), CH-1015, Lausanne, Switzerland
| | - Zelin Tan
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015, Lausanne, Switzerland
- Center of Quantum Science and Engineering (EPFL), CH-1015, Lausanne, Switzerland
| | - Mikhail Churaev
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015, Lausanne, Switzerland
- Center of Quantum Science and Engineering (EPFL), CH-1015, Lausanne, Switzerland
| | - Nikolai Kuznetsov
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015, Lausanne, Switzerland
- Center of Quantum Science and Engineering (EPFL), CH-1015, Lausanne, Switzerland
| | - Anat Siddharth
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015, Lausanne, Switzerland
- Center of Quantum Science and Engineering (EPFL), CH-1015, Lausanne, Switzerland
| | - Mohammad J Bereyhi
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015, Lausanne, Switzerland
- Center of Quantum Science and Engineering (EPFL), CH-1015, Lausanne, Switzerland
- Luxtelligence SA, CH-1015, Lausanne, Switzerland
| | - Johann Riemensberger
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015, Lausanne, Switzerland
- Center of Quantum Science and Engineering (EPFL), CH-1015, Lausanne, Switzerland
| | - Tobias J Kippenberg
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015, Lausanne, Switzerland.
- Center of Quantum Science and Engineering (EPFL), CH-1015, Lausanne, Switzerland.
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9
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Chen G, Chen K, Yu Z, Liu L. Low-loss and broadband polarization-diversity edge coupler on a thin-film lithium niobate platform. OPTICS LETTERS 2023; 48:4145-4148. [PMID: 37527139 DOI: 10.1364/ol.494891] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Accepted: 07/13/2023] [Indexed: 08/03/2023]
Abstract
Fiber-to-chip coupling is an essential issue for taking high-performance integrated photonic devices into practical applications. On a thin-film lithium niobate platform, such a high-performance coupler featuring low loss, large bandwidth, and polarization independence is highly desired. However, the mode hybridization induced by the birefringence of lithium niobate seriously restricts a polarization-independent coupling. Here, we propose and experimentally demonstrate a high-performance and polarization-diversity cantilever edge coupler (EC) with the assistance of a two-stage polarization splitter and rotator (PSR). The fabricated cantilever EC shows a minimal coupling loss of 1.06 dB/facet, and the fully etched PSR structure shows a low insertion loss (IL) of -0.62 dB. The whole polarization-diversity cantilever EC exhibits a low IL of -2.17 dB and -1.68 dB for TE0 and TM0 mode, respectively, as well as a small cross talk of <-15 dB covering the wavelength band from 1.5 µm to 1.6 µm. A polarization-dependent loss <0.5 dB over the same wavelength band is also obtained. The proposed fiber-to-waveguide coupler, compatible with the fabrication process of popular thin-film lithium niobate photonic devices, can work as a coupling scheme for on-chip polarization-diversity applications.
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Luo W, Cao L, Shi Y, Wan L, Zhang H, Li S, Chen G, Li Y, Li S, Wang Y, Sun S, Karim MF, Cai H, Kwek LC, Liu AQ. Recent progress in quantum photonic chips for quantum communication and internet. LIGHT, SCIENCE & APPLICATIONS 2023; 12:175. [PMID: 37443095 DOI: 10.1038/s41377-023-01173-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Subscribe] [Scholar Register] [Received: 08/07/2022] [Revised: 04/27/2023] [Accepted: 04/28/2023] [Indexed: 07/15/2023]
Abstract
Recent years have witnessed significant progress in quantum communication and quantum internet with the emerging quantum photonic chips, whose characteristics of scalability, stability, and low cost, flourish and open up new possibilities in miniaturized footprints. Here, we provide an overview of the advances in quantum photonic chips for quantum communication, beginning with a summary of the prevalent photonic integrated fabrication platforms and key components for integrated quantum communication systems. We then discuss a range of quantum communication applications, such as quantum key distribution and quantum teleportation. Finally, the review culminates with a perspective on challenges towards high-performance chip-based quantum communication, as well as a glimpse into future opportunities for integrated quantum networks.
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Affiliation(s)
- Wei Luo
- Quantum Science and Engineering Centre (QSec), Nanyang Technological University, Singapore, 639798, Singapore
| | - Lin Cao
- Quantum Science and Engineering Centre (QSec), Nanyang Technological University, Singapore, 639798, Singapore
| | - Yuzhi Shi
- Institute of Precision Optical Engineering, School of Physics Science and Engineering, Tongji University, 200092, Shanghai, China.
| | - Lingxiao Wan
- Quantum Science and Engineering Centre (QSec), Nanyang Technological University, Singapore, 639798, Singapore
| | - Hui Zhang
- Quantum Science and Engineering Centre (QSec), Nanyang Technological University, Singapore, 639798, Singapore
| | - Shuyi Li
- Quantum Science and Engineering Centre (QSec), Nanyang Technological University, Singapore, 639798, Singapore
| | - Guanyu Chen
- Quantum Science and Engineering Centre (QSec), Nanyang Technological University, Singapore, 639798, Singapore
| | - Yuan Li
- Quantum Science and Engineering Centre (QSec), Nanyang Technological University, Singapore, 639798, Singapore
| | - Sijin Li
- Quantum Science and Engineering Centre (QSec), Nanyang Technological University, Singapore, 639798, Singapore
| | - Yunxiang Wang
- School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, 610054, Chengdu, China
| | - Shihai Sun
- School of Electronics and Communication Engineering, Sun Yat-Sen University, 518100, Shenzhen, Guangdong, China
| | - Muhammad Faeyz Karim
- Quantum Science and Engineering Centre (QSec), Nanyang Technological University, Singapore, 639798, Singapore.
| | - Hong Cai
- Institute of Microelectronics, A*STAR (Agency for Science, Technology and Research), Singapore, 138634, Singapore.
| | - Leong Chuan Kwek
- Quantum Science and Engineering Centre (QSec), Nanyang Technological University, Singapore, 639798, Singapore.
- Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, Singapore, 117543, Singapore.
- National Institute of Education, Nanyang Technological University, Singapore, 637616, Singapore.
| | - Ai Qun Liu
- Quantum Science and Engineering Centre (QSec), Nanyang Technological University, Singapore, 639798, Singapore.
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11
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Yu Z, Yin Y, Huang X, Tu D, Yu H, Guan H, Jiang L, Yan W, Li Z. Silicon nitride assisted tri-layer edge coupler on lithium niobate-on-insulator platform. OPTICS LETTERS 2023; 48:3367-3370. [PMID: 37390132 DOI: 10.1364/ol.492372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 05/13/2023] [Indexed: 07/02/2023]
Abstract
Lithium niobate-on-insulator (LNOI) is a promising integration platform for various applications, such as optical communication, microwave photonics, and nonlinear optics. To make Lithium niobate (LN) photonic integrated circuits (PICs) more practical, low-loss fiber-chip coupling is essential. In this Letter, we propose and experimentally demonstrate a silicon nitride (SiN) assisted tri-layer edge coupler on LNOI platform. The edge coupler consists of a bilayer LN taper and an interlayer coupling structure composed of an 80 nm-thick SiN waveguide and an LN strip waveguide. The measured fiber-chip coupling loss for the TE mode is 0.75 dB/facet at 1550 nm. Transition loss between the SiN waveguide and LN strip waveguide is ∼0.15 dB. In addition, the fabrication tolerance of the SiN waveguide in the tri-layer edge coupler is high.
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12
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Churaev M, Wang RN, Riedhauser A, Snigirev V, Blésin T, Möhl C, Anderson MH, Siddharth A, Popoff Y, Drechsler U, Caimi D, Hönl S, Riemensberger J, Liu J, Seidler P, Kippenberg TJ. A heterogeneously integrated lithium niobate-on-silicon nitride photonic platform. Nat Commun 2023; 14:3499. [PMID: 37311746 DOI: 10.1038/s41467-023-39047-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 05/17/2023] [Indexed: 06/15/2023] Open
Abstract
The availability of thin-film lithium niobate on insulator (LNOI) and advances in processing have led to the emergence of fully integrated LiNbO3 electro-optic devices. Yet to date, LiNbO3 photonic integrated circuits have mostly been fabricated using non-standard etching techniques and partially etched waveguides, that lack the reproducibility achieved in silicon photonics. Widespread application of thin-film LiNbO3 requires a reliable solution with precise lithographic control. Here we demonstrate a heterogeneously integrated LiNbO3 photonic platform employing wafer-scale bonding of thin-film LiNbO3 to silicon nitride (Si3N4) photonic integrated circuits. The platform maintains the low propagation loss (<0.1 dB/cm) and efficient fiber-to-chip coupling (<2.5 dB per facet) of the Si3N4 waveguides and provides a link between passive Si3N4 circuits and electro-optic components with adiabatic mode converters experiencing insertion losses below 0.1 dB. Using this approach we demonstrate several key applications, thus providing a scalable, foundry-ready solution to complex LiNbO3 integrated photonic circuits.
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Affiliation(s)
- Mikhail Churaev
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015, Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland
| | - Rui Ning Wang
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015, Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland
| | - Annina Riedhauser
- IBM Research - Europe, Zurich, Säumerstrasse 4, CH-8803, Rüschlikon, Switzerland
| | - Viacheslav Snigirev
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015, Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland
| | - Terence Blésin
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015, Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland
| | - Charles Möhl
- IBM Research - Europe, Zurich, Säumerstrasse 4, CH-8803, Rüschlikon, Switzerland
| | - Miles H Anderson
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015, Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland
| | - Anat Siddharth
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015, Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland
| | - Youri Popoff
- IBM Research - Europe, Zurich, Säumerstrasse 4, CH-8803, Rüschlikon, Switzerland
- Integrated Systems Laboratory, Swiss Federal Institute of Technology Zurich (ETH Zürich), CH-8092, Zürich, Switzerland
| | - Ute Drechsler
- IBM Research - Europe, Zurich, Säumerstrasse 4, CH-8803, Rüschlikon, Switzerland
| | - Daniele Caimi
- IBM Research - Europe, Zurich, Säumerstrasse 4, CH-8803, Rüschlikon, Switzerland
| | - Simon Hönl
- IBM Research - Europe, Zurich, Säumerstrasse 4, CH-8803, Rüschlikon, Switzerland
| | - Johann Riemensberger
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015, Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland
| | - Junqiu Liu
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015, Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland
| | - Paul Seidler
- IBM Research - Europe, Zurich, Säumerstrasse 4, CH-8803, Rüschlikon, Switzerland.
| | - Tobias J Kippenberg
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), CH-1015, Lausanne, Switzerland.
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland.
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13
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Stokowski HS, McKenna TP, Park T, Hwang AY, Dean DJ, Celik OT, Ansari V, Fejer MM, Safavi-Naeini AH. Integrated quantum optical phase sensor in thin film lithium niobate. Nat Commun 2023; 14:3355. [PMID: 37291141 DOI: 10.1038/s41467-023-38246-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Accepted: 04/19/2023] [Indexed: 06/10/2023] Open
Abstract
The quantum noise of light, attributed to the random arrival time of photons from a coherent light source, fundamentally limits optical phase sensors. An engineered source of squeezed states suppresses this noise and allows phase detection sensitivity beyond the quantum noise limit (QNL). We need ways to use quantum light within deployable quantum sensors. Here we present a photonic integrated circuit in thin-film lithium niobate that meets these requirements. We use the second-order nonlinearity to produce a squeezed state at the same frequency as the pump light and realize circuit control and sensing with electro-optics. Using 26.2 milliwatts of optical power, we measure (2.7 ± 0.2)% squeezing and apply it to increase the signal-to-noise ratio of phase measurement. We anticipate that photonic systems like this, which operate with low power and integrate all of the needed functionality on a single die, will open new opportunities for quantum optical sensing.
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Affiliation(s)
- Hubert S Stokowski
- Department of Applied Physics and Ginzton Laboratory, Stanford University, Stanford, CA, 94305, USA
| | - Timothy P McKenna
- Physics & Informatics Laboratories, NTT Research, Inc., Sunnyvale, CA, 94085, USA
| | - Taewon Park
- Department of Applied Physics and Ginzton Laboratory, Stanford University, Stanford, CA, 94305, USA
- Department of Electrical Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Alexander Y Hwang
- Department of Applied Physics and Ginzton Laboratory, Stanford University, Stanford, CA, 94305, USA
| | - Devin J Dean
- Department of Applied Physics and Ginzton Laboratory, Stanford University, Stanford, CA, 94305, USA
| | - Oguz Tolga Celik
- Department of Applied Physics and Ginzton Laboratory, Stanford University, Stanford, CA, 94305, USA
- Department of Electrical Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Vahid Ansari
- Department of Applied Physics and Ginzton Laboratory, Stanford University, Stanford, CA, 94305, USA
| | - Martin M Fejer
- Department of Applied Physics and Ginzton Laboratory, Stanford University, Stanford, CA, 94305, USA
| | - Amir H Safavi-Naeini
- Department of Applied Physics and Ginzton Laboratory, Stanford University, Stanford, CA, 94305, USA.
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14
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Chen B, Ruan Z, Chen K, Liu L. One-dimensional grating coupler on lithium-niobate-on-insulator for high-efficiency and polarization-independent coupling. OPTICS LETTERS 2023; 48:1434-1437. [PMID: 36946946 DOI: 10.1364/ol.481277] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Accepted: 02/12/2023] [Indexed: 06/18/2023]
Abstract
A metal-based one-dimensional grating coupler on an x-cut lithium-niobate-on-insulator wafer structure for a polarization-independent fiber interface is designed and demonstrated. By using a metal-based plasmonic mode, the diffractive angle for the two polarized modes in the lithium niobate ridge waveguide can be tuned to be the same. The polarization dependence of the grating coupler therefore can be effectively reduced. The fabricated device exhibits -3.56-dB and -4.08-dB peak coupling losses per coupler at 1573 nm for the TE and TM modes, respectively. The polarization-dependent losses are less than 0.69 dB in a 44-nm wavelength range. The demonstrated grating coupler can serve as a polarization-independent optical fiber interface on lithium-niobate-on-insulator and facilitate on-chip polarization diversity applications.
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15
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He L, Feng H, Wang C, Chan HP. Cost-effective fiber-to-lithium niobate chip coupling using a double-side irradiation self-written waveguide. OPTICS LETTERS 2023; 48:283-286. [PMID: 36638438 DOI: 10.1364/ol.479820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Accepted: 12/09/2022] [Indexed: 06/17/2023]
Abstract
In recent years, integrated lithium niobate (LN) chips have been widely used for developing a variety of photonic devices, such as high-speed electro-optical (EO) modulators and frequency comb generators. A major challenge for their practical applications is the high coupling loss between micrometer-scale LN waveguides and optical fibers. Lensed fibers and special taper structures are commonly used to tackle the coupling issue. However, in some situations, these approaches may increase the overall complexity and cost of design, fabrication, and alignment. Here, we propose using the self-written waveguide (SWW), an optical waveguide induced by light irradiation, to cope with this coupling issue. The approach can apply in connecting a single-mode fiber (SMF) to any waveguide surface in principle, even with a large mode-field mismatch, significantly alleviating the tight alignment requirements typically needed for end-fire coupling into integrated waveguides. Our study demonstrates that the coupling loss between a SMF with a mode-field diameter (MFD) of 4.4 µm and a sub-micrometer LN rib waveguide could be dramatically reduced from an initial value of -14.27 dB to -5.61 dB, after double-side irradiated SWW formation. Our proposed approach offers a potential solution for achieving a cost-effective and flexible fiber-to-LN chip optical interconnect.
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16
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Yu M, Barton Iii D, Cheng R, Reimer C, Kharel P, He L, Shao L, Zhu D, Hu Y, Grant HR, Johansson L, Okawachi Y, Gaeta AL, Zhang M, Lončar M. Integrated femtosecond pulse generator on thin-film lithium niobate. Nature 2022; 612:252-258. [PMID: 36385531 DOI: 10.1038/s41586-022-05345-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 09/14/2022] [Indexed: 11/17/2022]
Abstract
Integrated femtosecond pulse and frequency comb sources are critical components for a wide range of applications, including optical atomic clocks1, microwave photonics2, spectroscopy3, optical wave synthesis4, frequency conversion5, communications6, lidar7, optical computing8 and astronomy9. The leading approaches for on-chip pulse generation rely on mode-locking inside microresonators with either third-order nonlinearity10 or with semiconductor gain11,12. These approaches, however, are limited in noise performance, wavelength and repetition rate tunability 10,13. Alternatively, subpicosecond pulses can be synthesized without mode-locking, by modulating a continuous-wave single-frequency laser using electro-optic modulators1,14-17. Here we demonstrate a chip-scale femtosecond pulse source implemented on an integrated lithium niobate photonic platform18, using cascaded low-loss electro-optic amplitude and phase modulators and chirped Bragg grating, forming a time-lens system19. The device is driven by a continuous-wave distributed feedback laser chip and controlled by a single continuous-wave microwave source without the need for any stabilization or locking. We measure femtosecond pulse trains (520-femtosecond duration) with a 30-gigahertz repetition rate, flat-top optical spectra with a 10-decibel optical bandwidth of 12.6 nanometres, individual comb-line powers above 0.1 milliwatts, and pulse energies of 0.54 picojoules. Our results represent a tunable, robust and low-cost integrated pulsed light source with continuous-wave-to-pulse conversion efficiencies an order of magnitude higher than those achieved with previous integrated sources. Our pulse generator may find applications in fields such as ultrafast optical measurement19,20 or networks of distributed quantum computers21,22.
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Affiliation(s)
- Mengjie Yu
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA.,Ming Hsieh Department of Electrical and Computer Engineering, University of Southern California, Los Angeles, CA, USA
| | - David Barton Iii
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Rebecca Cheng
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | | | | | | | - Linbo Shao
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Di Zhu
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | - Yaowen Hu
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA.,Department of Physics, Harvard University, Cambridge, MA, USA
| | | | | | - Yoshitomo Okawachi
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY, USA
| | - Alexander L Gaeta
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY, USA.,Department of Electrical Engineering, Columbia University, New York, NY, USA
| | | | - Marko Lončar
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA.
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17
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He X, Cortes-Herrera L, Opong-Mensah K, Zhang Y, Song M, Agrawal GP, Cardenas J. Electrically induced adiabatic frequency conversion in an integrated lithium niobate ring resonator. OPTICS LETTERS 2022; 47:5849-5852. [PMID: 37219118 DOI: 10.1364/ol.473113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Accepted: 10/15/2022] [Indexed: 05/24/2023]
Abstract
Changing the frequency of light outside the laser cavity is essential for an integrated photonics platform, especially when the optical frequency of the on-chip light source is fixed or challenging to be tuned precisely. Previous on-chip frequency conversion demonstrations of multiple GHz have limitations of tuning the shifted frequency continuously. To achieve continuous on-chip optical frequency conversion, we electrically tune a lithium niobate ring resonator to induce adiabatic frequency conversion. In this work, frequency shifts of up to 14.3 GHz are achieved by adjusting the voltage of an RF control. With this technique, we can dynamically control light in a cavity within its photon lifetime by tuning the refractive index of the ring resonator electrically.
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18
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Wang M, Li J, Yao H, Li X, Wu J, Chiang KS, Chen K. Thin-film lithium-niobate modulator with a combined passive bias and thermo-optic bias. OPTICS EXPRESS 2022; 30:39706-39715. [PMID: 36298916 DOI: 10.1364/oe.474594] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 10/05/2022] [Indexed: 06/16/2023]
Abstract
It is essential to bias a thin-film lithium-niobate Mach-Zehnder electro-optic (EO) modulator at the desired operation condition to ensure optimal performance of the modulator. While thermo-optic (TO) control can solve the problem of bias drift, it consumes significant electric power. In this paper, we propose a technique to largely reduce bias power consumption by combining passive bias and TO bias. In our design, waveguide sections with different widths are introduced in the two arms of the MZ modulator to produce a desired phase difference of π/2 rad (the desired operation condition), and local heating with electrode heaters placed on the waveguides is employed to provide compensation for any phase drift caused by fabrication errors and other effects. As the TO control only serves to compensate for small errors, the electric power required is low and the response is fast. To demonstrate our technique experimentally, we fabricate several modulators of the same design on the same chip. Our experimental modulators can operate up to ∼40 GHz with a half-wave voltage of ∼2.0 V over a wide optical bandwidth, and the performances are insensitive to ambient temperature variations. The TO bias powers required range from 1 mW to 15 mW, and the thermal rise and fall times are 47 µs and 14 µs, respectively. Our technique can facilitate the development of practical high-speed EO modulators on the lithium-niobate-on-insulator platform.
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19
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Liu X, Zhang C, Pan Y, Ma R, Zhang X, Chen M, Liu L, Xie Z, Zhu S, Yu S, Cai X. Thermally tunable and efficient second-harmonic generation on thin-film lithium niobate with integrated micro-heater. OPTICS LETTERS 2022; 47:4921-4924. [PMID: 36181151 DOI: 10.1364/ol.470867] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 08/25/2022] [Indexed: 06/16/2023]
Abstract
In this Letter, we report thermo-optic tunable and efficient second-harmonic generation (SHG) based on an X-cut periodically poled lithium niobate (PPLN) waveguide. By applying an on-chip heater with thermo-isolation trenches and combining a type-0 quasi-phase matching mechanism, we experimentally achieve a high on-chip SHG conversion efficiency of 2500-3000% W-1 cm-2 and a large tuning power efficiency of 94 pm/mW inside a single 5-mm-long straight PPLN waveguide. Our design is for energy-efficient, high-performance nonlinear applications, such as wavelength conversion, highly tunable coherent light sources, and photon-pair generation.
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20
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Xin CJ, Mishra J, Chen C, Zhu D, Shams-Ansari A, Langrock C, Sinclair N, Wong FNC, Fejer MM, Lončar M. Spectrally separable photon-pair generation in dispersion engineered thin-film lithium niobate. OPTICS LETTERS 2022; 47:2830-2833. [PMID: 35648941 DOI: 10.1364/ol.456873] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 05/05/2022] [Indexed: 06/15/2023]
Abstract
Existing nonlinear-optic implementations of pure, unfiltered heralded single-photon sources do not offer the scalability required for densely integrated quantum networks. Additionally, lithium niobate has hitherto been unsuitable for such use due to its material dispersion. We engineer the dispersion and the quasi-phasematching conditions of a waveguide in the rapidly emerging thin-film lithium niobate platform to generate spectrally separable photon pairs in the telecommunications band. Such photon pairs can be used as spectrally pure heralded single-photon sources in quantum networks. We estimate a heralded-state spectral purity of >94% based on joint spectral intensity measurements. Further, a joint spectral phase-sensitive measurement of the unheralded time-integrated second-order correlation function yields a heralded-state purity of (86±5)%.
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21
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On-chip electro-optic frequency shifters and beam splitters. Nature 2021; 599:587-593. [PMID: 34819680 DOI: 10.1038/s41586-021-03999-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 09/07/2021] [Indexed: 11/08/2022]
Abstract
Efficient frequency shifting and beam splitting are important for a wide range of applications, including atomic physics1,2, microwave photonics3-6, optical communication7,8 and photonic quantum computing9-14. However, realizing gigahertz-scale frequency shifts with high efficiency, low loss and tunability-in particular using a miniature and scalable device-is challenging because it requires efficient and controllable nonlinear processes. Existing approaches based on acousto-optics6,15-17, all-optical wave mixing10,13,18-22 and electro-optics23-27 are either limited to low efficiencies or frequencies, or are bulky. Furthermore, most approaches are not bi-directional, which renders them unsuitable for frequency beam splitters. Here we demonstrate electro-optic frequency shifters that are controlled using only continuous and single-tone microwaves. This is accomplished by engineering the density of states of, and coupling between, optical modes in ultralow-loss waveguides and resonators in lithium niobate nanophotonics28. Our devices, consisting of two coupled ring-resonators, provide frequency shifts as high as 28 gigahertz with an on-chip conversion efficiency of approximately 90 per cent. Importantly, the devices can be reconfigured as tunable frequency-domain beam splitters. We also demonstrate a non-blocking and efficient swap of information between two frequency channels with one of the devices. Finally, we propose and demonstrate a scheme for cascaded frequency shifting that allows shifts of 119.2 gigahertz using a 29.8 gigahertz continuous and single-tone microwave signal. Our devices could become building blocks for future high-speed and large-scale classical information processors7,29 as well as emerging frequency-domain photonic quantum computers9,11,14.
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22
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Xu Y, Sayem AA, Fan L, Zou CL, Wang S, Cheng R, Fu W, Yang L, Xu M, Tang HX. Bidirectional interconversion of microwave and light with thin-film lithium niobate. Nat Commun 2021; 12:4453. [PMID: 34294711 PMCID: PMC8298523 DOI: 10.1038/s41467-021-24809-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 07/01/2021] [Indexed: 11/09/2022] Open
Abstract
Superconducting cavity electro-optics presents a promising route to coherently convert microwave and optical photons and distribute quantum entanglement between superconducting circuits over long-distance. Strong Pockels nonlinearity and high-performance optical cavity are the prerequisites for high conversion efficiency. Thin-film lithium niobate (TFLN) offers these desired characteristics. Despite significant recent progresses, only unidirectional conversion with efficiencies on the order of 10-5 has been realized. In this article, we demonstrate the bidirectional electro-optic conversion in TFLN-superconductor hybrid system, with conversion efficiency improved by more than three orders of magnitude. Our air-clad device architecture boosts the sustainable intracavity pump power at cryogenic temperatures by suppressing the prominent photorefractive effect that limits cryogenic performance of TFLN, and reaches an efficiency of 1.02% (internal efficiency of 15.2%). This work firmly establishes the TFLN-superconductor hybrid EO system as a highly competitive transduction platform for future quantum network applications.
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Affiliation(s)
- Yuntao Xu
- Department of Electrical Engineering, Yale University, New Haven, CT, USA
| | - Ayed Al Sayem
- Department of Electrical Engineering, Yale University, New Haven, CT, USA
| | - Linran Fan
- Department of Electrical Engineering, Yale University, New Haven, CT, USA
- College of Optical Sciences, The University of Arizona, Tucson, AZ, USA
| | - Chang-Ling Zou
- Department of Electrical Engineering, Yale University, New Haven, CT, USA
| | - Sihao Wang
- Department of Electrical Engineering, Yale University, New Haven, CT, USA
| | - Risheng Cheng
- Department of Electrical Engineering, Yale University, New Haven, CT, USA
| | - Wei Fu
- Department of Electrical Engineering, Yale University, New Haven, CT, USA
| | - Likai Yang
- Department of Electrical Engineering, Yale University, New Haven, CT, USA
| | - Mingrui Xu
- Department of Electrical Engineering, Yale University, New Haven, CT, USA
| | - Hong X Tang
- Department of Electrical Engineering, Yale University, New Haven, CT, USA.
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23
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Lomonte E, Lenzini F, Pernice WHP. Efficient self-imaging grating couplers on a lithium-niobate-on-insulator platform at near-visible and telecom wavelengths. OPTICS EXPRESS 2021; 29:20205-20216. [PMID: 34266114 DOI: 10.1364/oe.428138] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Accepted: 05/26/2021] [Indexed: 06/13/2023]
Abstract
Lithium-niobate-on-insulator (LNOI) has emerged as a promising platform in the field of integrated photonics. Nonlinear optical processes and fast electro-optic modulation have been reported with outstanding performance in ultra-low loss waveguides. In order to harness the advantages offered by the LNOI technology, suitable fiber-to-chip interconnects operating at different wavelength ranges are demanded. Here we present easily manufacturable, self-imaging apodized grating couplers, featuring a coupling efficiency of the TE0 mode as high as ≃47.1% at λ=1550 nm and ≃44.9% at λ=775 nm. Our approach avoids the use of any metal back-reflector for an improved directivity or multi-layer structures for an enhanced grating strength.
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24
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Li L, Ma Y, Zhang Y, Li S, Shi Y, Chen X. Multi-tip edge coupler for integration of a distributed feedback semiconductor laser with a thin-film lithium niobate modulator. APPLIED OPTICS 2021; 60:4814-4819. [PMID: 34143034 DOI: 10.1364/ao.425773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 05/11/2021] [Indexed: 06/12/2023]
Abstract
Lithium niobate-on-insulator (LNOI) has been emerging as a popular integration platform for optical communications and microwave photonics. An edge coupler with high coupling efficiency, wide bandwidth, high fabrication and misalignment tolerance, as well as a small footprint is essential to couple light in or out of the LNOI chip. Some edge couplers have been demonstrated to realize fiber-to-chip coupling in the last few years, but the coupling with distributed feedback (DFB) semiconductor laser is rarely studied. In this paper, we propose a multi-tip edge coupler with three tips to reduce the mode size mismatch between the LNOI waveguide and the DFB laser. The tilted sidewall, fabrication tolerance, misalignment tolerance, and facet reflection due to the effective index mismatch are discussed. It shows that the proposed multi-tip edge coupler can be practically used in the production of effective LNOI integrated chips.
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25
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Ying P, Tan H, Zhang J, He M, Xu M, Liu X, Ge R, Zhu Y, Liu C, Cai X. Low-loss edge-coupling thin-film lithium niobate modulator with an efficient phase shifter. OPTICS LETTERS 2021; 46:1478-1481. [PMID: 33720216 DOI: 10.1364/ol.418996] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Accepted: 02/22/2021] [Indexed: 06/12/2023]
Abstract
Thin-film lithium-niobate-on-insulator (LNOI) is a very attractive platform for optical interconnect and nonlinear optics. It is essential to enable lithium niobate photonic integrated circuits with low power consumption. Here we present an edge-coupling Mach-Zehnder modulator on the platform with low fiber-chip coupling loss of 0.5 dB/facet, half-wave voltage Vπ of 2.36 V, electro-optic (EO) bandwidth of 60 GHz and an efficient thermal-optic phase shifter with half-wave power of 6.24 mW. In addition, we experimentally demonstrate single-lane 200 Gbit/s data transmission utilizing a discrete multi-tone signal. The LNOI modulator demonstrated here shows great potential in energy-efficient large-capacity optical interconnects.
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26
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Zhang M, Chen K, Wang M, Wu J, Chiang KS. Electro-optic reconfigurable two-mode (de)multiplexer on thin-film lithium niobate. OPTICS LETTERS 2021; 46:1001-1004. [PMID: 33649639 DOI: 10.1364/ol.417423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 01/25/2021] [Indexed: 06/12/2023]
Abstract
We propose and demonstrate a compact electro-optic reconfigurable two-mode (de)multiplexer using the configuration of cascaded Mach-Zehnder interferometers formed on thin-film X-cut lithium niobate on silica. Our fabricated device, which is 9.5-mm long, can spatially switch between the two transverse-electric modes with an efficiency higher than 98% from 1530-1560 nm and beyond at an applied voltage of 6.5 V. The switching speed is faster than 30 ns. Our proposed mode switch could find applications in fiber-based and on-chip mode-division-multiplexing systems.
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27
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Hu C, Pan A, Li T, Wang X, Liu Y, Tao S, Zeng C, Xia J. High-efficient coupler for thin-film lithium niobate waveguide devices. OPTICS EXPRESS 2021; 29:5397-5406. [PMID: 33726076 DOI: 10.1364/oe.416492] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 01/26/2021] [Indexed: 06/12/2023]
Abstract
Lithium niobate (LN) devices have been widely used in optical communication and nonlinear optics due to its attractive optical properties. The emergence of the thin-film lithium niobate on insulator (LNOI) improves performances of LN-based devices greatly. However, a high-efficient fiber-chip optical coupler is still necessary for the LNOI-based devices for practical applications. In this paper, we demonstrate a highly efficient and polarization-independent edge coupler based on LNOI. The coupler, fabricated by a standard semiconductor process, shows a low fiber-chip coupling loss of 0.54 dB/0.59 dB per facet at 1550 nm for TE/TM light, respectively, when coupled with an ultra-high numerical aperture fiber (UHNAF) of which the mode field diameter is about 3.2 μm. The coupling loss is lower than 1dB/facet for both TE and TM light in the wavelength range of 1527 nm to 1630 nm. A relatively large tolerance for optical misalignment is also proved, due to the coupler's large mode spot size up to 3.2 μm. The coupler shows a promising stability in high optical power and temperature variation.
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Chen B, Ruan Z, Hu J, Wang J, Lu C, Lau APT, Guo C, Chen K, Chen P, Liu L. Two-dimensional grating coupler on an X-cut lithium niobate thin-film. OPTICS EXPRESS 2021; 29:1289-1295. [PMID: 33726347 DOI: 10.1364/oe.413820] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 12/21/2020] [Indexed: 06/12/2023]
Abstract
A two-dimensional grating coupler for coupling light between a standard single-mode fiber and ridge waveguides on an X-cut lithium niobate thin-film is designed and demonstrated. Using circular holes for grating cells, simulated coupling losses reach -3.88 dB at 1550 nm and -5.78 dB at 1563 nm with 1-dB bandwidths of 49 nm and 45 nm for P-polarized and S-polarized light inputs, respectively. Experimentally, peak coupling losses of -5.13 dB at 1561 nm and -7.6 dB at 1568 nm are obtained for P-polarized and S-polarized light inputs, respectively, and corresponding 1 dB bandwidths are about 30 nm. An approach to improve the coupling performance of the grating coupler is also proposed using two crossing ellipses as grating cells as well as a bottom metal reflector. The coupling loss and the polarization dependent loss are decreased to around -3.4 dB and 0.44 dB, respectively.
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Li Z, Lin P, Huang YW, Park JS, Chen WT, Shi Z, Qiu CW, Cheng JX, Capasso F. Meta-optics achieves RGB-achromatic focusing for virtual reality. SCIENCE ADVANCES 2021; 7:7/5/eabe4458. [PMID: 33571130 PMCID: PMC7840120 DOI: 10.1126/sciadv.abe4458] [Citation(s) in RCA: 65] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 12/14/2020] [Indexed: 05/08/2023]
Abstract
Virtual and augmented realities are rapidly developing technologies, but their large-scale penetration will require lightweight optical components with small aberrations. We demonstrate millimeter-scale diameter, high-NA, submicron-thin, metasurface-based lenses that achieve diffraction-limited achromatic focusing of the primary colors by exploiting constructive interference of light from multiple zones and dispersion engineering. To illustrate the potential of this approach, we demonstrate a virtual reality system based on a home-built fiber scanning near-eye display.
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Affiliation(s)
- Zhaoyi Li
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA.
| | - Peng Lin
- Department of Electrical and Computer Engineering, Boston University, Boston, MA 02215, USA
| | - Yao-Wei Huang
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
| | - Joon-Suh Park
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
- Nanophotonics Research Center, Korea Institute of Science and Technology, Seoul, Republic of Korea
| | - Wei Ting Chen
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| | - Zhujun Shi
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | - Cheng-Wei Qiu
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
| | - Ji-Xin Cheng
- Department of Electrical and Computer Engineering, Boston University, Boston, MA 02215, USA
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA
| | - Federico Capasso
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA.
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Elkus BS, Abdelsalam K, Fathpour S, Kumar P, Kanter GS. Quantum-correlated photon-pair generation via cascaded nonlinearity in an ultra-compact lithium-niobate nano-waveguide. OPTICS EXPRESS 2020; 28:39963-39975. [PMID: 33379534 DOI: 10.1364/oe.411575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 12/05/2020] [Indexed: 06/12/2023]
Abstract
We generate quantum-correlated photon pairs using cascaded χ(2):χ(2) traveling-wave interactions for second-harmonic generation (SHG) and spontaneous parametric down-conversion (SPDC) in a single periodically-poled thin-film lithium-niobate (TFLN) waveguide. When pulse-pumped at 50 MHz, a 4-mm-long poled region with nearly 300%/Wcm2 SHG peak efficiency yields a generated photon-pair probability of 7±0.2 × 10-4 with corresponding coincidence-to-accidental ratio (CAR) of 13.6±0.7. The CAR is found to be limited by Stokes/anti-Stokes Raman-scattering noise generated primarily in the waveguide. A Raman peak of photon counts at 250 cm-1 Stokes shift from the fundamental-pump wavenumber suggests most of the noise that limits the CAR originates within the lithium niobate material of the waveguide.
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Liu Y, Huang X, Li Z, Guan H, Wei Q, Fan Z, Han W, Li Z. Efficient grating couplers on a thin film lithium niobate-silicon rich nitride hybrid platform. OPTICS LETTERS 2020; 45:6847-6850. [PMID: 33325911 DOI: 10.1364/ol.413246] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Accepted: 11/27/2020] [Indexed: 06/12/2023]
Abstract
A grating coupler on a thin film x-cut lithium niobate-silicon rich nitride hybrid platform is proposed and demonstrated. An inverse taper is applied to suppress higher-order mode excitation. A coupling efficiency of -5.82dB and 3 dB bandwidth of 57 nm are obtained near the wavelength of 1550 nm between the standard single-mode fiber (SMF-28) and sub-micrometer waveguides.
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32
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Kang S, Zhang R, Hao Z, Jia D, Gao F, Bo F, Zhang G, Xu J. High-efficiency chirped grating couplers on lithium niobate on insulator. OPTICS LETTERS 2020; 45:6651-6654. [PMID: 33325860 DOI: 10.1364/ol.412902] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 11/07/2020] [Indexed: 06/12/2023]
Abstract
High-efficiency chirped grating couplers (GCs) with coupling efficiencies (CE) approaching 90%/coupler were designed by using a particle swarm optimization algorithm. These GCs were fabricated on $z$-cut lithium niobate on insulator (LNOI) with an Au layer on the lithium niobate substrate. The maximum CEs for transverse electric and transverse magnetic polarization input were measured up to ${\sim}{72.0}\%$/coupler and ${\sim}{61.6}\%$/coupler, respectively, which are the state-of-the-art values for LNOI GCs as far as we know. These GCs contribute to the realization of high-efficiency LNOI on-chip integrated optics.
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Ruan Z, Hu J, Xue Y, Liu J, Chen B, Wang J, Chen K, Chen P, Liu L. Metal based grating coupler on a thin-film lithium niobate waveguide. OPTICS EXPRESS 2020; 28:35615-35621. [PMID: 33379673 DOI: 10.1364/oe.411284] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 11/01/2020] [Indexed: 06/12/2023]
Abstract
Thin-film lithium niobate (LN) has been proved to be an excellent platform for building compact active and nonlinear photonic components on a chip. The coupling of a sub-micron sized LN waveguide and a single-mode fiber remains as one challenging issue. An efficient grating coupler made of Au stripes on an LN ridge waveguide is demonstrated here. The fabrication of the grating is convenient, using just a standard lift-off process of metal films. The peak coupling efficiency of an optimized structure reaches 50.4%, i.e., -3 dB coupling loss, at 1.55 µm wavelength for the fundamental transverse-electrical mode, where the 1-dB coupling bandwidth is 58 nm. Experimentally, fabricated devices, with buried oxide layer thicknesses slightly off the optimal values, exhibit coupling efficiencies of 43.8% and 33.7% for 400 nm and 600 nm thick LN layers.
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Mode hybridization analysis in thin film lithium niobate strip multimode waveguides. Sci Rep 2020; 10:16692. [PMID: 33028905 PMCID: PMC7542427 DOI: 10.1038/s41598-020-73936-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 09/23/2020] [Indexed: 11/08/2022] Open
Abstract
Mode hybridization phenomenon in air-cladded X-cut Y-propagating and Z-propagating thin film lithium niobate strip multimode waveguides is numerically studied and a mathematical relation between structural parameters leading to hybrid modes is formulated. Dependence of hybrid modes on waveguide dimensions, sidewall angles and wavelength is also analyzed. The results obtained are used to design lithium niobate on insulator (LNOI) taper for converting fundamental TM mode to higher order TE mode, and an optimum length for achieving a high conversion efficiency of 99.5% is evaluated. Birefringent Y-propagating LN and isotropic Z-propagating LN tapers are compared in terms of length, figures of merit, and fabrication tolerance. Tapers exhibit a broad bandwidth of 200 nm with an extinction ratio less than − 18 dB. The results of mode hybridization analysis are useful in design optimization of adiabatic tapers, tunable time delays, optical interconnects, mode converters and demultiplexers for mode division multiplexing (MDM) applications.
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Kores CC, Fokine M, Laurell F. UV-written grating couplers on thin-film lithium niobate ridge waveguides. OPTICS EXPRESS 2020; 28:27839-27849. [PMID: 32988068 DOI: 10.1364/oe.396667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 08/20/2020] [Indexed: 06/11/2023]
Abstract
Grating couplers on thin-film lithium niobate ridge waveguides were designed and fabricated using UV-laser ablation. The calculated coupling efficiency with a sinusoidal grating can be as large as 53% in a 0.5 µm thin film. The maximum grating depth we fabricated was 130nm, limiting the coupling efficiency to a theoretical value of 18%. We fabricated grating couplers on adhered ridge waveguides of 20 µm thickness. Coupling light to waveguides on thin-film lithium niobate is still challenging, and here we present a fast, cheap and reliable fabrication alternative. It will benefit the on-chip testing of integrated components developed on this novel and promising material platform.
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Shao L, Sinclair N, Leatham J, Hu Y, Yu M, Turpin T, Crowe D, Lončar M. Integrated microwave acousto-optic frequency shifter on thin-film lithium niobate. OPTICS EXPRESS 2020; 28:23728-23738. [PMID: 32752365 DOI: 10.1364/oe.397138] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 07/20/2020] [Indexed: 06/11/2023]
Abstract
Electrically driven acousto-optic devices that provide beam deflection and optical frequency shifting have broad applications from pulse synthesis to heterodyne detection. Commercially available acousto-optic modulators are based on bulk materials and consume Watts of radio frequency power. Here, we demonstrate an integrated 3-GHz acousto-optic frequency shifter on thin-film lithium niobate, featuring a carrier suppression over 30 dB. Further, we demonstrate a gigahertz-spaced optical frequency comb featuring more than 200 lines over a 0.6-THz optical bandwidth by recirculating the light in an active frequency shifting loop. Our integrated acousto-optic platform leads to the development of on-chip optical routing, isolation, and microwave signal processing.
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Li Y, Lan T, Li J, Wang Z. High-efficiency edge-coupling based on lithium niobate on an insulator wire waveguide. APPLIED OPTICS 2020; 59:6694-6701. [PMID: 32749374 DOI: 10.1364/ao.395897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 07/05/2020] [Indexed: 06/11/2023]
Abstract
Edge-coupling on single-crystal thin-film lithium niobate on insulator (LNOI) was systematically studied in this paper. An inverse taper-shaped spot-size converter (SSC) to convert the mode field from the laser chip to a nanoscale LNOI waveguide was adopted to improve the coupling efficiency. Structure of the edge coupler was fully investigated and optimized by using the eigenmode expansion method. The single-mode conditions of the LNOI waveguide for three common communication bands were taken into consideration. Further, the length and tip width of the inverse taper, the cross-section dimensions of SiON waveguide, and the sidewall angle were investigated with respect to coupling efficiency. As a result, the maximum coupling efficiency from an edge coupler to laser chip can reach 54%, 48%, and 58% at 1550, 1310, and 850 nm in Z-cut LNOI for quasi-TM mode, respectively. This proposed work gives a better understanding of the function of the edge coupler based on LNOI material and provides an appropriate method for the design of an edge coupler with high efficiency, which could benefit the further application of high-density monolithic integrated optical components.
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Wang M, Li J, Chen K, Hu Z. Thin-film lithium niobate electro-optic modulator on a D-shaped fiber. OPTICS EXPRESS 2020; 28:21464-21473. [PMID: 32752423 DOI: 10.1364/oe.396613] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 06/29/2020] [Indexed: 06/11/2023]
Abstract
We propose a low-insertion-loss electro-optic modulator formed with LNOI bonded on a D-shaped SMF. The proposed modulator employs high-performance Mach-Zehnder interferometer (MZI) formed with ridge LNOI waveguides and driven by travelling-wave electrodes. The light from the fiber core is coupled into a thin strip LNOI waveguide and then launched into the MZI via a ridge LNOI waveguide with tapered slab height and vice versa. Such all-fiber configuration exempts the need of the butt-coupling with an SMF. The calculated results show that our proposed modulator is capable of achieving a low insertion loss of less than 1.5 dB, an EO modulation efficiency (Vπ·L) of 2.05 V·cm, and a 3-dB modulation bandwidth of larger than 80 GHz. Our all-fiber LNOI modulator is feasible in practice and opens a new door to realize high-speed fiber devices by the integration of an optical fiber and thin film LN.
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Zhao J, Rüsing M, Javid UA, Ling J, Li M, Lin Q, Mookherjea S. Shallow-etched thin-film lithium niobate waveguides for highly-efficient second-harmonic generation. OPTICS EXPRESS 2020; 28:19669-19682. [PMID: 32672239 DOI: 10.1364/oe.395545] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 06/15/2020] [Indexed: 06/11/2023]
Abstract
High-fidelity periodic poling over long lengths is required for robust, quasi-phase-matched second-harmonic generation using the fundamental, quasi-TE polarized waveguide modes in a thin-film lithium niobate (TFLN) waveguide. Here, a shallow-etched ridge waveguide is fabricated in x-cut magnesium oxide doped TFLN and is poled accurately over 5 mm. The high fidelity of the poling is demonstrated over long lengths using a non-destructive technique of confocal scanning second-harmonic microscopy. We report a second-harmonic conversion efficiency of up to 939 %.W-1 (length-normalized conversion efficiency 3757 %.W-1.cm-2), measured at telecommunications wavelengths. The device demonstrates a narrow spectral linewidth (1 nm) and can be tuned precisely with a tuning characteristic of 0.1 nm/°C, over at least 40 °C without measurable loss of efficiency.
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Yao N, Zhou J, Gao R, Lin J, Wang M, Cheng Y, Fang W, Tong L. Efficient light coupling between an ultra-low loss lithium niobate waveguide and an adiabatically tapered single mode optical fiber. OPTICS EXPRESS 2020; 28:12416-12423. [PMID: 32403739 DOI: 10.1364/oe.391228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 03/31/2020] [Indexed: 06/11/2023]
Abstract
A lithium niobate on an insulator ridge waveguide allows constructing high-density photonic integrated circuits thanks to its small bending radius offered by the high index contrast. Meanwhile, the significant mode-field mismatch between an optical fiber and the single-mode lithium niobate waveguide leads to low coupling efficiencies. Here, we demonstrate, both numerically and experimentally, that the problem can be solved with a tapered single mode fiber of an optimized mode field profile. Numerical simulation shows that the minimum coupling losses for the TE and TM mode are 0.32 dB and 0.86 dB, respectively. Experimentally, though without anti-reflection coating, the measured coupling losses for TE and TM mode are 1.32 dB and 1.88 dB, respectively. Our technique paves a way for a broad range of on-chip lithium niobate applications.
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Xu H, Dai D, Liu L, Shi Y. Proposal for an ultra-broadband polarization beam splitter using an anisotropy-engineered Mach-Zehnder interferometer on the x-cut lithium-niobate-on-insulator. OPTICS EXPRESS 2020; 28:10899-10908. [PMID: 32403611 DOI: 10.1364/oe.390075] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 03/24/2020] [Indexed: 06/11/2023]
Abstract
We propose and theoretically demonstrate an integrated polarization beam splitter on the x-cut lithium-niobate-on-insulator (LNOI) platform. The device is based on a Mach-Zehnder interferometer with an anisotropy-engineered multi-section phase shifter. The phase shift can be simultaneously controlled for the TE and TM polarizations by engineering the length and direction of the anisotropic LNOI waveguide. For TE polarization, the phase shift is -π/2, while for TM polarization, the phase shift is π/2. Thus, the incident TE and TM modes can be coupled into different output ports. The simulation results show an ultra-high polarization extinction ratio of ∼47.7 dB, a low excess loss of ∼0.9 dB and an ultra-broad working bandwidth of ∼200 nm. To the best of our knowledge, the proposed structure is the first integrated polarization beam splitter on the x-cut LNOI platform.
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Dutta S, Goldschmidt EA, Barik S, Saha U, Waks E. Integrated Photonic Platform for Rare-Earth Ions in Thin Film Lithium Niobate. NANO LETTERS 2020; 20:741-747. [PMID: 31855433 DOI: 10.1021/acs.nanolett.9b04679] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Rare-earth ion ensembles doped in single crystals are a promising materials system with widespread applications in optical signal processing, lasing, and quantum information processing. Incorporating rare-earth ions into integrated photonic devices could enable compact lasers and modulators, as well as on-chip optical quantum memories for classical and quantum optical applications. To this end, a thin film single crystalline wafer structure that is compatible with planar fabrication of integrated photonic devices would be highly desirable. However, incorporating rare-earth ions into a thin film form-factor while preserving their optical properties has proven challenging. We demonstrate an integrated photonic platform for rare-earth ions doped in a single crystalline thin film lithium niobate on insulator. The thin film is composed of lithium niobate doped with Tm3+. The ions in the thin film exhibit optical lifetimes identical to those measured in bulk crystals. We show narrow spectral holes in a thin film waveguide that require up to 2 orders of magnitude lower power to generate than previously reported bulk waveguides. Our results pave the way for scalable on-chip lasers, optical signal processing devices, and integrated optical quantum memories.
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Affiliation(s)
- Subhojit Dutta
- Department of Electrical and Computer Engineering, Institute for Research in Electronics and Applied Physics, and Joint Quantum Institute , University of Maryland , College Park , Maryland 20742 , United States
| | - Elizabeth A Goldschmidt
- Department of Physics , University of Illinois at Urbana-Champaign , Urbana , Illinois 61801 , United States
| | - Sabyasachi Barik
- Department of Electrical and Computer Engineering, Institute for Research in Electronics and Applied Physics, and Joint Quantum Institute , University of Maryland , College Park , Maryland 20742 , United States
| | - Uday Saha
- Department of Electrical and Computer Engineering, Institute for Research in Electronics and Applied Physics, and Joint Quantum Institute , University of Maryland , College Park , Maryland 20742 , United States
| | - Edo Waks
- Department of Electrical and Computer Engineering, Institute for Research in Electronics and Applied Physics, and Joint Quantum Institute , University of Maryland , College Park , Maryland 20742 , United States
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Elkus BS, Abdelsalam K, Rao A, Velev V, Fathpour S, Kumar P, Kanter GS. Generation of broadband correlated photon-pairs in short thin-film lithium-niobate waveguides. OPTICS EXPRESS 2019; 27:38521-38531. [PMID: 31878617 DOI: 10.1364/oe.27.038521] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Accepted: 11/24/2019] [Indexed: 06/10/2023]
Abstract
An efficient source of quantum-correlated photon-pairs that is integrable with existing silicon-electronics fabrication techniques is desirable for use in quantum photonic integrated circuits. Here we demonstrate signal-idler photon pairs with high coincidence-to-accidental count ratios of over 103 on a coarse wavelength-division-multiplexing grid that spans 140 nm by using a 300-μm-long poled region in a thin-film periodically-poled lithium-niobate ridge waveguide bonded to silicon. The pairs are generated via spontaneous parametric downconversion pumped by a continuous-wave tunable laser source. The small mode area of the waveguide allows for efficient interaction in a short length of the waveguide and, as a result, permits photon-pair generation over a broad range of signal-idler wavelengths.
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