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Fang S, Hong B, Lv L, Shen R, Zhao H, Chu W, Cai H, Huang W. Design and fabrication of a sub-3 dB grating coupler on an X-cut thin-film lithium niobate platform. OPTICS LETTERS 2024; 49:5519-5522. [PMID: 39352996 DOI: 10.1364/ol.530942] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2024] [Accepted: 08/26/2024] [Indexed: 10/04/2024]
Abstract
Thin-film lithium niobate (TFLN) based integrated photonic devices have been intensively investigated due to their promising properties, enabling various on-chip applications. Grating couplers (GCs) are wildly used for their flexibility and high alignment tolerance for fiber-to-chip coupling. However, achieving high coupling efficiency (CE) in TFLN GCs often requires the use of reflectors, hybrid materials, or extremely narrow linewidths of the grating arrays, which significantly increases the fabrication difficulty. Therefore, there is a demand for high-CE GCs on TFLN with simple structure and easy fabrication processes. In this paper, combining process capabilities, we demonstrate a highly efficient apodized GC by linearly optimizing the period length and the fill factor on a 600-nm-thick TFLN platform. Without any reflector or hybrid material, we achieve a remarkable coupling loss of -2.97 dB at 1555 nm on the 600-nm-thick X-cut TFLN platform with only a single lithography and etching step. Our work sets a new benchmark for CE among GCs on the 600-nm-thick TFLN platform.
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2
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Wu L, Xing X, Ruan Z, Gan R, Qi L, Wang H, Guo C, Chen K, Liu L. Polarization-insensitive multimode interference coupler on an x-cut thin-film lithium niobate platform. OPTICS LETTERS 2024; 49:4409-4412. [PMID: 39090946 DOI: 10.1364/ol.533030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2024] [Accepted: 07/15/2024] [Indexed: 08/04/2024]
Abstract
Thin-film lithium niobate (TFLN) is a promising integrated photonics platform but currently lacks a polarization-insensitive multimode interference (MMI) coupler, a crucial component for polarization-related optical communication applications such as polarization management, polarization-division multiplexing, and polarization-insensitive modulation systems. This paper presents a novel, to the best of our knowledge, approach by rotating the MMI structure on an anisotropic x-cut TFLN at specific angles to compensate for the difference in the beat length between the two polarizations. A polarization-insensitive 1 × 2 MMI coupler is experimentally achieved with measured transmittances of -2.5 to -4 dB for both output ports and polarization modes in the wavelength range of 1520-1580 nm.
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3
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Li Y, Sun M, Miao T, Chen J. Towards High-Performance Pockels Effect-Based Modulators: Review and Projections. MICROMACHINES 2024; 15:865. [PMID: 39064376 PMCID: PMC11278586 DOI: 10.3390/mi15070865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2024] [Revised: 06/26/2024] [Accepted: 06/27/2024] [Indexed: 07/28/2024]
Abstract
The ever-increasing demand for high-speed data transmission in telecommunications and data centers has driven the development of advanced on-chip integrated electro-optic modulators. Silicon modulators, constrained by the relatively weak carrier dispersion effect, face challenges in meeting the stringent requirements of next-generation photonic integrated circuits. Consequently, there has been a growing interest in Pockels effect-based electro-optic modulators, leveraging ferroelectric materials like LiNbO3, BaTiO3, PZT, and LaTiO3. Attributed to the large first-order electro-optic coefficient, researchers have delved into developing modulators with expansive bandwidth, low power consumption, compact size, and linear response. This paper reviews the working principles, fabrication techniques, integration schemes, and recent highlights in Pockels effect-based modulators.
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Affiliation(s)
- Yu Li
- State Key Laboratory of Advanced Optical Communication Systems and Networks, Department of Electronic Engineering, Shanghai Jiao Tong University, Shanghai 200240, China; (Y.L.); (M.S.); (T.M.)
- SJTU-Pinghu Institute of Intelligent Optoelectronics, Pinghu 314200, China
| | - Muhan Sun
- State Key Laboratory of Advanced Optical Communication Systems and Networks, Department of Electronic Engineering, Shanghai Jiao Tong University, Shanghai 200240, China; (Y.L.); (M.S.); (T.M.)
| | - Ting Miao
- State Key Laboratory of Advanced Optical Communication Systems and Networks, Department of Electronic Engineering, Shanghai Jiao Tong University, Shanghai 200240, China; (Y.L.); (M.S.); (T.M.)
| | - Jianping Chen
- State Key Laboratory of Advanced Optical Communication Systems and Networks, Department of Electronic Engineering, Shanghai Jiao Tong University, Shanghai 200240, China; (Y.L.); (M.S.); (T.M.)
- SJTU-Pinghu Institute of Intelligent Optoelectronics, Pinghu 314200, China
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4
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Hou S, Hu H, Liu Z, Xing W, Zhang J, Hao Y. High-Speed Electro-Optic Modulators Based on Thin-Film Lithium Niobate. NANOMATERIALS (BASEL, SWITZERLAND) 2024; 14:867. [PMID: 38786823 PMCID: PMC11124123 DOI: 10.3390/nano14100867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2024] [Revised: 05/02/2024] [Accepted: 05/09/2024] [Indexed: 05/25/2024]
Abstract
Electro-optic modulators (EOMs) are pivotal in bridging electrical and optical domains, essential for diverse applications including optical communication, microwave signal processing, sensing, and quantum technologies. However, achieving the trifecta of high-density integration, cost-effectiveness, and superior performance remains challenging within established integrated photonics platforms. Enter thin-film lithium niobate (LN), a recent standout with its inherent electro-optic (EO) efficiency, proven industrial performance, durability, and rapid fabrication advancements. This platform inherits material advantages from traditional bulk LN devices while offering a reduced footprint, wider bandwidths, and lower power requirements. Despite its recent introduction, commercial thin-film LN wafers already rival or surpass established alternatives like silicon and indium phosphide, benefitting from decades of research. In this review, we delve into the foundational principles and technical innovations driving state-of-the-art LN modulator demonstrations, exploring various methodologies, their strengths, and challenges. Furthermore, we outline pathways for further enhancing LN modulators and anticipate exciting prospects for larger-scale LN EO circuits beyond singular components. By elucidating the current landscape and future directions, we highlight the transformative potential of thin-film LN technology in advancing electro-optic modulation and integrated photonics.
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Affiliation(s)
- Songyan Hou
- Guangzhou Institute of Technology, Xidian University, Guangzhou 510555, China; (Z.L.); (W.X.)
- State Key Laboratory of Wide Bandgap Semiconductor Devices and Integrated Technology, School of Microelectronics, Xidian University, Xi’an 710071, China;
| | - Hao Hu
- National Key Laboratory of Microwave Photonics, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, China;
| | - Zhihong Liu
- Guangzhou Institute of Technology, Xidian University, Guangzhou 510555, China; (Z.L.); (W.X.)
- State Key Laboratory of Wide Bandgap Semiconductor Devices and Integrated Technology, School of Microelectronics, Xidian University, Xi’an 710071, China;
| | - Weichuan Xing
- Guangzhou Institute of Technology, Xidian University, Guangzhou 510555, China; (Z.L.); (W.X.)
- State Key Laboratory of Wide Bandgap Semiconductor Devices and Integrated Technology, School of Microelectronics, Xidian University, Xi’an 710071, China;
| | - Jincheng Zhang
- State Key Laboratory of Wide Bandgap Semiconductor Devices and Integrated Technology, School of Microelectronics, Xidian University, Xi’an 710071, China;
| | - Yue Hao
- State Key Laboratory of Wide Bandgap Semiconductor Devices and Integrated Technology, School of Microelectronics, Xidian University, Xi’an 710071, China;
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5
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Liu L, Chen WT, Zhao J, Zhang C. Two Structural Designs of Broadband, Low-Loss, and Compact TM Magneto-Optical Isolator Based on GaAs-on-Insulator. NANOMATERIALS (BASEL, SWITZERLAND) 2024; 14:400. [PMID: 38470731 DOI: 10.3390/nano14050400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 02/18/2024] [Accepted: 02/19/2024] [Indexed: 03/14/2024]
Abstract
Integrated optical isolators are important building blocks for photonic integrated chips. Despite significant advances in isolators integrated on silicon-on-insulator (SOI) platforms, integrated isolators on GaAs-on-insulator platforms are rarely reported. In this paper, two structural designs of optical isolators based on the TM basic mode of GaAs-on-insulator are proposed. The non-reciprocal phase shift (NRPS) of GaAs/Ce:YIG waveguides with different geometric structures are calculated using numerical simulation. The isolators achieve 35 dB isolation bandwidths greater than 53.5 nm and 70 nm at 1550 nm, with total insertion losses of 2.59 dB and 2.25 dB, respectively. A multi-mode interferometric (MMI) coupler suitable for these two structures is proposed. In addition, suitable manufacturing processes are discussed based on the simulated process tolerances.
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Affiliation(s)
- Li Liu
- School of Information Science and Engineering, Shandong University, Qingdao 266237, China
| | - Wan-Ting Chen
- School of Information Science and Engineering, Shandong University, Qingdao 266237, China
| | - Jia Zhao
- School of Information Science and Engineering, Shandong University, Qingdao 266237, China
| | - Chen Zhang
- School of Information Science and Engineering, Shandong University, Qingdao 266237, China
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6
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Kumar CHSSP, Klimov NN, Kuo PS. Optimization of waveguide fabrication processes in lithium-niobate-on-insulator platform. AIP ADVANCES 2024; 14:10.1063/6.0003522. [PMID: 38915883 PMCID: PMC11194688 DOI: 10.1063/6.0003522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/26/2024]
Abstract
Lithium niobate (LN) is used in diverse applications such as spectroscopy, remote sensing, and quantum communications. The emergence of lithium-niobate-on-insulator (LNOI) technology and its commercial accessibility represent significant milestones. This technology aids in harnessing the full potential of LN's properties, such as achieving tight mode confinement and strong overlap with applied electric fields, which has enabled LNOI-based electro-optic modulators to have ultra-broad bandwidths with low-voltage operation and low power consumption. Consequently, LNOI devices are emerging as competitive contenders in the integrated photonics landscape. However, the nanofabrication, particularly LN etching, presents a notable challenge. LN is hard, dense, and chemically inert. It has anisotropic etch behavior and a propensity to produce material redeposition during the reactive-ion plasma etch process. These factors make fabricating low-loss LNOI waveguides (WGs) challenging. Recognizing the pivotal role of addressing these fabrication challenges for obtaining low-loss WGs, our research focuses on a systematic study of various process steps in fabricating LNOI WGs and other photonic structures. In particular, our study involves (i) careful selection of hard mask materials, (ii) optimization of inductively coupled plasma etch parameters, and finally, (iii) determining the optimal post-etch cleaning approach to remove redeposited material on the sidewalls of the etched photonic structures. Using the recipe established, we realized optical WGs with total (propagation and coupling) loss value of -10.5 dB, comparable to established values found in the literature. Our findings broaden our understanding of optimizing fabrication processes for low-loss lithium-niobate waveguides and can serve as an accessible resource in advancing LNOI technology.
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Affiliation(s)
- CH. S. S. Pavan Kumar
- Information Technology Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899
| | - Nikolai N. Klimov
- Physical Measurement Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899
| | - Paulina S. Kuo
- Information Technology Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899
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7
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Hemsley E, Gauthier-Lafaye O, Monmayrant A, Dubreuil P, Calvez S, Fehrembach AL, Popov E. Critical coupling in cavity-resonant integrated-grating filters (CRIGFs). OPTICS EXPRESS 2023; 31:27274-27286. [PMID: 37710806 DOI: 10.1364/oe.498125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Accepted: 07/13/2023] [Indexed: 09/16/2023]
Abstract
We experimentally demonstrate critical coupling in miniature grating-coupled resonators known as cavity-resonant integrated-grating filters (CRIGFs). Using previously proposed asymmetric grating coupler designs for non-linear CRIGFs, and introducing a dedicated variant of a coupled-modes theory model to estimate physical properties out of the measured reflection and transmission characteristics of these resonators, we demonstrate fine control over the in-and out-coupling rate to the resonator while keeping constant both the internal losses and the resonant wavelength. Furthermore, the critical coupling condition is also observed to coincide with the maximum enhancement of the second harmonic generation signal.
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8
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Lin Y, Ke W, Ma R, Huang F, Tan H, Xu J, Lin Z, Cai X. Arbitrary-ratio 1 × 2 optical power splitter based on thin-film lithium niobate. OPTICS EXPRESS 2023; 31:27266-27273. [PMID: 37710805 DOI: 10.1364/oe.497887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 07/16/2023] [Indexed: 09/16/2023]
Abstract
Optical power splitters (OPSs) have been widely used in photonic integrated circuits, but an OPS with a large fabrication tolerance and free choice of power splitting ratio (PSR) is still highly desired for thin-film lithium niobate (TFLN) platform. Here, we propose and experimentally demonstrate several 1 × 2 OPSs with PSRs from 50:50 to 5:95 using TFLN platform. The proposed devices are built by multimode interference structure to achieve a broad bandwidth and large fabrication tolerance. Various PSRs can be obtained by adjusting the geometry structure of the multimode interference region. All of our fabricated devices feature an insertion loss lower than 0.3 dB at the wavelength of 1550 nm, and a PSR variation less than 3% in the range of 1520 nm to 1590 nm.
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9
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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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10
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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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11
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Wei C, Li J, Jia Q, Li D, Liu J. Ultrahigh-Q lithium niobate microring resonator with multimode waveguide. OPTICS LETTERS 2023; 48:2465-2467. [PMID: 37126299 DOI: 10.1364/ol.489387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Difficulty in etching lithium niobate (LN) results in a relatively high propagation loss, which necessitates sophisticated processes to fabricate high-quality factor (Q) microresonators. Here, we fabricate a multimode microring resonator with an intrinsic Q of 6 × 106, which exhibits a propagation loss 50 times lower than that of a single-mode LN microring fabricated under the same process. Notably, the excitation of higher-order modes in the multimode microring is effectively suppressed by utilizing the Euler bend. The highly regular transmission spectrum of the resonator demonstrates a free spectral range (FSR) of 56 GHz. Based on this microresonator, we implement a bandpass microwave photonic filter with an ultra-narrow 3 dB bandwidth of 47.5 MHz and a large tuning range of 2-26.5 GHz. It can be anticipated that the combination of existing advanced etching techniques with this work will drive the propagation loss of a LN waveguide closer to the material absorption loss, significantly facilitating the optimization of performance in applications requiring ultrahigh-Q LN microresonators, such as frequency combs, frequency conversion, electro-optic modulation, and quantum photonics.
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12
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Li Y, Lan T, Yang D, Bao J, Xiang M, Yang F, Wang Z. High-Performance Mach-Zehnder Modulator Based on Thin-Film Lithium Niobate with Low Voltage-Length Product. ACS OMEGA 2023; 8:9644-9651. [PMID: 36936308 PMCID: PMC10018726 DOI: 10.1021/acsomega.3c00310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 02/14/2023] [Indexed: 06/18/2023]
Abstract
Electro-optic modulators (EOMs) based on a thin-film lithium niobate (TFLN) photonic integration platform play a crucial role in loading electrical signals onto optical signals. In this paper, we proposed on-chip EOMs operating at two commercially available wavelengths of 850 and 1550 nm and successfully demonstrated rather low voltage-length products (V π ·Ls) of 0.78 V·cm and 1.29 V·cm, respectively. Additionally, the EOM working at 1550 nm exhibits the capability of 3-dB electro-optic (E-O) bandwidth beyond 40 GHz due to the limitation of our test conditions. This study is quite helpful for understanding EOM structures in a TFLN platform, as well as the fabrication of high-performance and multifunctional EOM devices.
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Affiliation(s)
- Ying Li
- Beijing Engineering
Research
Center of Laser Technology, Beijing University
of Technology, Beijing 100124, China
- Key Laboratory of
Trans-scale
Laser Manufacturing Technology (Beijing University of Technology), Ministry of Education, Beijing 100124, China
- Institute of Advanced Technology
on Semiconductor Optics & Electronics, Institute of Laser Engineering, Beijing University of Technology, Beijing 100124, China
| | | | - Dengcai Yang
- Beijing Engineering
Research
Center of Laser Technology, Beijing University
of Technology, Beijing 100124, China
- Key Laboratory of
Trans-scale
Laser Manufacturing Technology (Beijing University of Technology), Ministry of Education, Beijing 100124, China
- Institute of Advanced Technology
on Semiconductor Optics & Electronics, Institute of Laser Engineering, Beijing University of Technology, Beijing 100124, China
| | - Jianfeng Bao
- Beijing Engineering
Research
Center of Laser Technology, Beijing University
of Technology, Beijing 100124, China
- Key Laboratory of
Trans-scale
Laser Manufacturing Technology (Beijing University of Technology), Ministry of Education, Beijing 100124, China
- Institute of Advanced Technology
on Semiconductor Optics & Electronics, Institute of Laser Engineering, Beijing University of Technology, Beijing 100124, China
| | - Meihua Xiang
- Beijing Engineering
Research
Center of Laser Technology, Beijing University
of Technology, Beijing 100124, China
- Key Laboratory of
Trans-scale
Laser Manufacturing Technology (Beijing University of Technology), Ministry of Education, Beijing 100124, China
- Institute of Advanced Technology
on Semiconductor Optics & Electronics, Institute of Laser Engineering, Beijing University of Technology, Beijing 100124, China
| | - Feng Yang
- Beijing Engineering
Research
Center of Laser Technology, Beijing University
of Technology, Beijing 100124, China
- Key Laboratory of
Trans-scale
Laser Manufacturing Technology (Beijing University of Technology), Ministry of Education, Beijing 100124, China
- Institute of Advanced Technology
on Semiconductor Optics & Electronics, Institute of Laser Engineering, Beijing University of Technology, Beijing 100124, China
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13
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Snigirev V, Riedhauser A, Lihachev G, Churaev M, Riemensberger J, Wang RN, Siddharth A, Huang G, Möhl C, Popoff Y, Drechsler U, Caimi D, Hönl S, Liu J, Seidler P, Kippenberg TJ. Ultrafast tunable lasers using lithium niobate integrated photonics. Nature 2023; 615:411-417. [PMID: 36922611 PMCID: PMC10017507 DOI: 10.1038/s41586-023-05724-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 01/11/2023] [Indexed: 03/17/2023]
Abstract
Early works1 and recent advances in thin-film lithium niobate (LiNbO3) on insulator have enabled low-loss photonic integrated circuits2,3, modulators with improved half-wave voltage4,5, electro-optic frequency combs6 and on-chip electro-optic devices, with applications ranging from microwave photonics to microwave-to-optical quantum interfaces7. Although recent advances have demonstrated tunable integrated lasers based on LiNbO3 (refs. 8,9), the full potential of this platform to demonstrate frequency-agile, narrow-linewidth integrated lasers has not been achieved. Here we report such a laser with a fast tuning rate based on a hybrid silicon nitride (Si3N4)-LiNbO3 photonic platform and demonstrate its use for coherent laser ranging. Our platform is based on heterogeneous integration of ultralow-loss Si3N4 photonic integrated circuits with thin-film LiNbO3 through direct bonding at the wafer level, in contrast to previously demonstrated chiplet-level integration10, featuring low propagation loss of 8.5 decibels per metre, enabling narrow-linewidth lasing (intrinsic linewidth of 3 kilohertz) by self-injection locking to a laser diode. The hybrid mode of the resonator allows electro-optic laser frequency tuning at a speed of 12 × 1015 hertz per second with high linearity and low hysteresis while retaining the narrow linewidth. Using a hybrid integrated laser, we perform a proof-of-concept coherent optical ranging (FMCW LiDAR) experiment. Endowing Si3N4 photonic integrated circuits with LiNbO3 creates a platform that combines the individual advantages of thin-film LiNbO3 with those of Si3N4, which show precise lithographic control, mature manufacturing and ultralow loss11,12.
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Affiliation(s)
- Viacheslav Snigirev
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland
| | | | - Grigory Lihachev
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland
| | - Mikhail Churaev
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland
| | - Johann Riemensberger
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland
- Deep Light SA
| | - Rui Ning Wang
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland
| | - Anat Siddharth
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland
| | - Guanhao Huang
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland
| | - Charles Möhl
- IBM Research - Europe, Zurich, Ruschlikon, Switzerland
| | - Youri Popoff
- IBM Research - Europe, Zurich, Ruschlikon, Switzerland
- Integrated Systems Laboratory, Swiss Federal Institute of Technology Zurich (ETH Zürich), Zurich, Switzerland
| | - Ute Drechsler
- IBM Research - Europe, Zurich, Ruschlikon, Switzerland
| | - Daniele Caimi
- IBM Research - Europe, Zurich, Ruschlikon, Switzerland
| | - Simon Hönl
- IBM Research - Europe, Zurich, Ruschlikon, Switzerland
| | - Junqiu Liu
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland
| | - Paul Seidler
- IBM Research - Europe, Zurich, Ruschlikon, Switzerland.
| | - Tobias J Kippenberg
- Institute of Physics, Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland.
- Center for Quantum Science and Engineering, EPFL, Lausanne, Switzerland.
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14
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Wang F, Liu H, Ma T, Ma S, Liu Y. Polarization beam splitter based on the asymmetric directional coupler of lithium niobate film. APPLIED OPTICS 2023; 62:21-26. [PMID: 36606844 DOI: 10.1364/ao.476196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 11/28/2022] [Indexed: 06/17/2023]
Abstract
A polarization beam splitter (PBS) based on a lithium niobate film asymmetric directional coupler is proposed. The PBS is located on a lithium niobate platform on an insulator consisting of a silicon nitride-lithium niobate waveguide (SLW) and a lithium niobate waveguide (LNW). By rationally designing the SLW and LNW sizes, TE polarization satisfies the phase matching condition and TM polarization phase mismatch. The numerical simulation results show that the extinction ratio (ER) and insertion loss (IL) of PBS for TE mode are 30.57 and 0.66 dB, respectively, and the ER and IL of PBS for TM mode are 28.15 and 0.11 dB, respectively, at an operating wavelength of 1.55 µm.
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15
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Ghoname AO, Hassanien AE, Chow E, Goddard LL, Gong S. Highly linear lithium niobate Michelson interferometer modulators assisted by spiral Bragg grating reflectors. OPTICS EXPRESS 2022; 30:40666-40681. [PMID: 36298997 DOI: 10.1364/oe.472673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 10/05/2022] [Indexed: 06/16/2023]
Abstract
Highly linear electro-optic modulators are key components in analog microwave photonic links, offering on-chip direct mixing of optical and RF fields. In this work, we demonstrate a monolithic integrated Michelson interferometer modulator on thin-film lithium niobate (LN), that achieves linearized performance by modulating Bragg grating reflectors placed at the end of Michelson arms. The modulator utilizes spiral-shaped waveguide Bragg gratings on Z-cut LN with top and bottom electrodes to realize extensive reflectors, essential for linearized performance, in a highly integrated form. Optical waveguides are realized using rib etching of LN with precisely engineered bottom and top cladding layers made of silicon dioxide and SU-8 polymer, respectively. The compact design fits a 3 mm long grating in an 80 µm × 80 µm area, achieving a broad operating bandwidth up to 18 GHz. A spurious free dynamic range (SFDR) of 101.2 dB·Hz2/3 is demonstrated at 1 GHz, compared to 91.5 dB·Hz2/3 for a reference Mach-Zehnder modulator fabricated on the same chip. Further enhancement in SFDR could be achieved by reducing fiber-to-chip coupling loss. The proposed demonstration could significantly improve the linearity of analog modulator-based integrated optical links.
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16
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High-Performance Electro-Optical Mach–Zehnder Modulators in a Silicon Nitride–Lithium Niobate Thin-Film Hybrid Platform. PHOTONICS 2022. [DOI: 10.3390/photonics9070500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We analyzed a Mach–Zehnder electro-optical modulator based on a silicon nitride strip–loaded waveguide on 0.5 μm thick x-cut lithium niobate thin film. The optical and radio frequency parameters for two different modulator structures (Type I: packaged with 2 μm thick SiO2 and Type II: unpackaged) were simulated, calculated, and optimized. The Optical parameters included the single-mode conditions, effective indices, the separation distance between the electrode edge and the Si3N4-strip-loaded edge, optical power distribution, bending loss, optical field distribution, and half-wave voltage. The radio frequency parameters included the characteristic impedance, attenuation constant, radio frequency effective index, and −3 dB modulation bandwidth. According to the numerical simulation and theoretical analysis, the half-wave voltage product and the −3 dB modulation bandwidth were, respectively, 2.85 V·cm and 0.4 THz for Type I modulator, and 2.33 V·cm and 1.26 THz for Type II modulator, with a device length of 3 mm.
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17
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Zhang X, Kang K, Jiang Y, He J, Qiao Y. Double-layer focal plane microscopy for high throughput DNA sequencing. OPTICS EXPRESS 2022; 30:18496-18504. [PMID: 36221649 DOI: 10.1364/oe.454100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Accepted: 02/23/2022] [Indexed: 06/16/2023]
Abstract
Throughput is one of the most important properties in DNA sequencing. We propose a novel double-layer focal plane microscopy that doubles the DNA sequencing throughput. Each fluorescence channel is divided into two tube lens channels by energy splitting, and the camera is adjusted to take images corresponding to different defocus positions of the objective, thus doubling the information capacity of the microscopy. The microscopy is applied to gene chip, which has high spatial frequency and good uniformity, so the simultaneous imaging of the two tubes has little influence on each other due to the spatial averaging effect. Experimental results show that the image signal to noise ratio (SNR) is reduced by 1%, while the sequencing throughput is doubled.
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18
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Hassanien AE, Ghoname AO, Chow E, Goddard LL, Gong S. Compact MZI modulators on thin film Z-cut lithium niobate. OPTICS EXPRESS 2022; 30:4543-4552. [PMID: 35209688 DOI: 10.1364/oe.446665] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 01/20/2022] [Indexed: 06/14/2023]
Abstract
In this paper, we designed, implemented, and characterized compact Mach-Zehnder interferometer-based electro-optic modulators. The modulator utilizes spiral-shaped optical waveguides on Z-cut lithium niobate and the preeminent electro-optic effect which is applied using top and bottom electrodes. Optical waveguides are made of rib etched lithium niobate waveguides with bottom silicon oxide cladding, while SU8 polymer covers the top and sides of the rib waveguides. The proposed implementation resulted in low optical losses < 1.3 dB/cm. Moreover, we achieved compact modulators that fit 0.286 cm and 2 cm long optical waveguides in 110 µm × 110 µm and 300 µm × 300 µm areas, respectively. For single arm modulation, the modulators achieved a VπL of 7.4 V.cm and 6.4 V.cm and 3-dB bandwidths of 9.3 GHz and 2.05 GHz, respectively. Push-pull modulation is expected to cut these VπL in half. The proposed configuration avoids traveling wave modulation complexities and represents a key development towards miniature and highly integrated photonic circuits.
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19
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Yang G, Sergienko AV, Ndao A. Tunable polarization mode conversion using thin-film lithium niobate ridge waveguide. OPTICS EXPRESS 2021; 29:18565-18571. [PMID: 34154110 DOI: 10.1364/oe.426672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 05/24/2021] [Indexed: 06/13/2023]
Abstract
Lithium niobate on insulator (LNOI) waveguides, as an emerging technology, have proven to offer a promising platform for integrated optics, due to their strong optical confinement comparable to silicon on insulator (SOI) waveguides, while possessing the versatile properties of lithium niobate, such as high electro-optic coefficients. In this paper, we show that mode hybridization, a phenomenon widely found in vertically asymmetric waveguides, can be efficiently modulated in an LNOI ridge waveguide by electro-optic effect, leading to a polarization mode converter with 97% efficiency. Moreover, the proposed device does not require tapering or periodic poling, thereby greatly simplifying the fabrication process. It can also be actively switched by external fields. Such a platform facilitates technological progress of photonics circuits and sensors.
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20
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Kim Y, Han JH, Ahn D, Kim S. Heterogeneously-Integrated Optical Phase Shifters for Next-Generation Modulators and Switches on a Silicon Photonics Platform: A Review. MICROMACHINES 2021; 12:625. [PMID: 34071362 PMCID: PMC8230192 DOI: 10.3390/mi12060625] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 05/24/2021] [Accepted: 05/25/2021] [Indexed: 01/23/2023]
Abstract
The realization of a silicon optical phase shifter marked a cornerstone for the development of silicon photonics, and it is expected that optical interconnects based on the technology relax the explosive datacom growth in data centers. High-performance silicon optical modulators and switches, integrated into a chip, play a very important role in optical transceivers, encoding electrical signals onto the light at high speed and routing the optical signals, respectively. The development of the devices is continuously required to meet the ever-increasing data traffic at higher performance and lower cost. Therefore, heterogeneous integration is one of the highly promising approaches, expected to enable high modulation efficiency, low loss, low power consumption, small device footprint, etc. Therefore, we review heterogeneously integrated optical modulators and switches for the next-generation silicon photonic platform.
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Affiliation(s)
- Younghyun Kim
- Department of Photonics and Nanoelectronics, BK21 FOUR ERICA-ACE Center, Hanyang University, Ansan 15588, Korea;
| | - Jae-Hoon Han
- Center for Opto-Electronic Materials and Devices, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea;
| | - Daehwan Ahn
- Center for Opto-Electronic Materials and Devices, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea;
| | - Sanghyeon Kim
- School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea;
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21
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An Ultra-High-Q Lithium Niobate Microresonator Integrated with a Silicon Nitride Waveguide in the Vertical Configuration for Evanescent Light Coupling. MICROMACHINES 2021; 12:mi12030235. [PMID: 33669092 PMCID: PMC7996522 DOI: 10.3390/mi12030235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 02/18/2021] [Accepted: 02/21/2021] [Indexed: 11/16/2022]
Abstract
We demonstrate the hybrid integration of a lithium niobate microring resonator with a silicon nitride waveguide in the vertical configuration to achieve efficient light coupling. The microring resonator is fabricated on a lithium niobate on insulator (LNOI) substrate using photolithography assisted chemo-mechanical etching (PLACE). A fused silica cladding layer is deposited on the LNOI ring resonator. The silicon nitride waveguide is further produced on the fused silica cladding layer by first fabricating a trench in the fused silica while using focused ion beam (FIB) etching for facilitating the evanescent coupling, followed by the formation of the silicon nitride waveguide on the bottom of the trench. The FIB etching ensures the required high positioning accuracy between the waveguide and ring resonator. We achieve Q-factors as high as 1.4 × 107 with the vertically integrated device.
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22
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Chen G, Cheung EJH, Cao Y, Pan J, Danner AJ. Analysis of perovskite oxide etching using argon inductively coupled plasmas for photonics applications. NANOSCALE RESEARCH LETTERS 2021; 16:32. [PMID: 33569658 PMCID: PMC7876212 DOI: 10.1186/s11671-021-03494-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 02/03/2021] [Indexed: 06/12/2023]
Abstract
We analyzed the dry etching of perovskite oxides using argon-based inductively coupled plasmas (ICP) for photonics applications. Various chamber conditions and their effects on etching rates have been demonstrated based on Z-cut lithium niobate (LN). The measured results are predictable and repeatable and can be applied to other perovskite oxides, such as X-cut LN and barium titanium oxide (BTO). The surface roughness is better for both etched LN and BTO compared with their as-deposited counterparts as confirmed by atomic force microscopy (AFM). Both the energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) methods have been used for surface chemical component comparisons, qualitative and quantitative, and no obvious surface state changes are observed according to the measured results. An optical waveguide fabricated with the optimized argon-based ICP etching was measured to have -3.7 dB/cm loss near 1550 nm wavelength for Z-cut LN, which validates this kind of method for perovskite oxides etching in photonics applications.
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Affiliation(s)
- Guanyu Chen
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore, 117583, Singapore
| | - Eric Jun Hao Cheung
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore, 117583, Singapore
| | - Yu Cao
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore, 117583, Singapore
| | - Jisheng Pan
- Institute of Materials Research and Engineering, A∗STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, Innovis #08-03, Singapore, 138634, Singapore
| | - Aaron J Danner
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore, 117583, Singapore.
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23
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Fedotova A, Younesi M, Sautter J, Vaskin A, Löchner FJF, Steinert M, Geiss R, Pertsch T, Staude I, Setzpfandt F. Second-Harmonic Generation in Resonant Nonlinear Metasurfaces Based on Lithium Niobate. NANO LETTERS 2020; 20:8608-8614. [PMID: 33180501 DOI: 10.1021/acs.nanolett.0c03290] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Lithium niobate is an excellent and widely used material for nonlinear frequency conversion due to its strong optical nonlinearity and broad transparency region. Here, we report the fabrication and experimental investigation of resonant nonlinear metasurfaces for second-harmonic generation based on thin-film lithium niobate. In the fabricated metasurfaces, we observe pronounced Mie-type resonances leading to enhanced second-harmonic generation in the direction normal to the metasurface. We find the largest second-harmonic generation efficiency for the resonance dominated by the electric contributions because its specific field distribution enables the most efficient usage of the largest element of the lithium niobate nonlinear susceptibility tensor. This is confirmed by polarization-resolved second-harmonic measurements, where we study contributions from different elements of the nonlinear susceptibility tensor to the total second-harmonic signal. Our work facilitates establishing lithium niobate as a material for resonant nanophotonics.
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Affiliation(s)
- Anna Fedotova
- Institute of Applied Physics, Abbe Center of Photonics, Friedrich Schiller University Jena, 07745 Jena, Germany
| | - Mohammadreza Younesi
- Institute of Applied Physics, Abbe Center of Photonics, Friedrich Schiller University Jena, 07745 Jena, Germany
| | - Jürgen Sautter
- Institute of Applied Physics, Abbe Center of Photonics, Friedrich Schiller University Jena, 07745 Jena, Germany
| | - Aleksandr Vaskin
- Institute of Applied Physics, Abbe Center of Photonics, Friedrich Schiller University Jena, 07745 Jena, Germany
| | - Franz J F Löchner
- Institute of Applied Physics, Abbe Center of Photonics, Friedrich Schiller University Jena, 07745 Jena, Germany
| | - Michael Steinert
- Institute of Applied Physics, Abbe Center of Photonics, Friedrich Schiller University Jena, 07745 Jena, Germany
| | - Reinhard Geiss
- Institute of Applied Physics, Abbe Center of Photonics, Friedrich Schiller University Jena, 07745 Jena, Germany
| | - Thomas Pertsch
- Institute of Applied Physics, Abbe Center of Photonics, Friedrich Schiller University Jena, 07745 Jena, Germany
- Fraunhofer Institute of Applied Optics and Precision Engineering, 07745 Jena, Germany
| | - Isabelle Staude
- Institute of Applied Physics, Abbe Center of Photonics, Friedrich Schiller University Jena, 07745 Jena, Germany
| | - Frank Setzpfandt
- Institute of Applied Physics, Abbe Center of Photonics, Friedrich Schiller University Jena, 07745 Jena, Germany
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24
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Luke K, Kharel P, Reimer C, He L, Loncar M, Zhang M. Wafer-scale low-loss lithium niobate photonic integrated circuits. OPTICS EXPRESS 2020; 28:24452-24458. [PMID: 32906986 DOI: 10.1364/oe.401959] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 07/27/2020] [Indexed: 06/11/2023]
Abstract
Thin-film lithium niobate (LN) photonic integrated circuits (PICs) could enable ultrahigh performance in electro-optic and nonlinear optical devices. To date, realizations have been limited to chip-scale proof-of-concepts. Here we demonstrate monolithic LN PICs fabricated on 4- and 6-inch wafers with deep ultraviolet lithography and show smooth and uniform etching, achieving 0.27 dB/cm optical propagation loss on wafer-scale. Our results show that LN PICs are fundamentally scalable and can be highly cost-effective.
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25
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Dai J, Xu R, Lin YS, Chen CH. Tunable electromagnetic characteristics of suspended nanodisk metasurface. OPTICS & LASER TECHNOLOGY 2020; 128:106214. [DOI: doi.org/10.1016/j.optlastec.2020.106214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
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26
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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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27
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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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28
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Rao A, Abdelsalam K, Sjaardema T, Honardoost A, Camacho-Gonzalez GF, Fathpour S. Actively-monitored periodic-poling in thin-film lithium niobate photonic waveguides with ultrahigh nonlinear conversion efficiency of 4600 %W -1cm -2. OPTICS EXPRESS 2019; 27:25920-25930. [PMID: 31510454 DOI: 10.1364/oe.27.025920] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Chip-scale implementations of second-order nonlinear optics benefit from increased optical confinement that can lead to nonlinear interaction strengths that are orders of magnitude higher than bulk free-space configurations. Here, we present thin-film-based ultraefficient periodically-poled lithium niobate nonlinear waveguides, leveraging actively-monitored ferroelectric domain reversal engineering and nanophotonic confinement. The devices exhibit up to 4600 %W-1cm-2 conversion efficiency for second-harmonic generation, pumped around 1540 nm. In addition, we measure broadband sum-frequency generation across multiple telecom bands, from 1460 to 1620 nm. As an immediate application of the devices, we use pulses of picojoule-level energy to demonstrate second-harmonic generation with over 10% conversion in a 0.6-mm-long waveguide. Our ultracompact and highly efficient devices address growing demands in integrated-photonic frequency conversion, frequency metrology, atomic physics, and quantum optics, while offering a coherent link between the telecom and visible bands.
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29
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Rusing M, Weigel PO, Zhao J, Mookherjea S. Toward 3D Integrated Photonics Including Lithium Niobate Thin Films: A Bridge Between Electronics, Radio Frequency, and Optical Technology. IEEE NANOTECHNOLOGY MAGAZINE 2019. [DOI: 10.1109/mnano.2019.2916115] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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30
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Krasnokutska I, Tambasco JLJ, Peruzzo A. Tunable large free spectral range microring resonators in lithium niobate on insulator. Sci Rep 2019; 9:11086. [PMID: 31366897 PMCID: PMC6668402 DOI: 10.1038/s41598-019-47231-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2018] [Accepted: 06/25/2019] [Indexed: 12/04/2022] Open
Abstract
Microring resonators are critical photonic components used in filtering, sensing and nonlinear applications. To date, the development of high performance microring resonators in LNOI has been limited by the sidewall angle, roughness and etch depth of fabricated rib waveguides. We present large free spectral range microring resonators patterned via electron beam lithography in high-index contrast Z-cut LNOI. Our microring resonators achieve an FSR greater than 5 nm for ring radius of 30 μm and a large 3 dB resonance bandwidth. We demonstrate 3 pm/V electro-optic tuning of a 70 μm-radius ring. This work will enable efficient on-chip filtering in LNOI and precede future, more complex, microring resonator networks and nonlinear field enhancement applications.
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Affiliation(s)
- Inna Krasnokutska
- Quantum Photonics Laboratory and Centre for Quantum Computation and Communication Technology, School of Engineering, RMIT University, Melbourne, Victoria, 3000, Australia
| | - Jean-Luc J Tambasco
- Quantum Photonics Laboratory and Centre for Quantum Computation and Communication Technology, School of Engineering, RMIT University, Melbourne, Victoria, 3000, Australia
| | - Alberto Peruzzo
- Quantum Photonics Laboratory and Centre for Quantum Computation and Communication Technology, School of Engineering, RMIT University, Melbourne, Victoria, 3000, Australia.
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31
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Xu Q, Shao Y, Piao R, Chen F, Wang X, Yang X, Wong W, Pun EY, Zhang D. A Theoretical Study on Rib‐Type Photonic Wires Based on LiNbO
3
Thin Film on Insulator. ADVANCED THEORY AND SIMULATIONS 2019. [DOI: 10.1002/adts.201900115] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Qing Xu
- Department of Opto‐electronics and Information EngineeringSchool of Precision Instruments and Opto‐electronics EngineeringKey Laboratory of Optoelectronic Information Science & Technology (Ministry of Education)Tianjin University Tianjin 300072 China
| | - Yan‐Xue Shao
- Department of Opto‐electronics and Information EngineeringSchool of Precision Instruments and Opto‐electronics EngineeringKey Laboratory of Optoelectronic Information Science & Technology (Ministry of Education)Tianjin University Tianjin 300072 China
| | - Rui‐Qi Piao
- Department of Opto‐electronics and Information EngineeringSchool of Precision Instruments and Opto‐electronics EngineeringKey Laboratory of Optoelectronic Information Science & Technology (Ministry of Education)Tianjin University Tianjin 300072 China
| | - Feng Chen
- Department of Opto‐electronics and Information EngineeringSchool of Precision Instruments and Opto‐electronics EngineeringKey Laboratory of Optoelectronic Information Science & Technology (Ministry of Education)Tianjin University Tianjin 300072 China
| | - Xiao Wang
- Department of Opto‐electronics and Information EngineeringSchool of Precision Instruments and Opto‐electronics EngineeringKey Laboratory of Optoelectronic Information Science & Technology (Ministry of Education)Tianjin University Tianjin 300072 China
| | - Xiao‐Fei Yang
- Department of Opto‐electronics and Information EngineeringSchool of Precision Instruments and Opto‐electronics EngineeringKey Laboratory of Optoelectronic Information Science & Technology (Ministry of Education)Tianjin University Tianjin 300072 China
| | - Wing‐Han Wong
- Department of Electronic EngineeringState Key Laboratory of Terahertz and Millimeter WavesCity University of Hong Kong Hong Kong China
| | - Edwin Yue‐Bun Pun
- Department of Electronic EngineeringState Key Laboratory of Terahertz and Millimeter WavesCity University of Hong Kong Hong Kong China
| | - De‐Long Zhang
- Department of Opto‐electronics and Information EngineeringSchool of Precision Instruments and Opto‐electronics EngineeringKey Laboratory of Optoelectronic Information Science & Technology (Ministry of Education)Tianjin University Tianjin 300072 China
- Department of Electronic EngineeringState Key Laboratory of Terahertz and Millimeter WavesCity University of Hong Kong Hong Kong China
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32
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Bahadori M, Yang Y, Goddard LL, Gong S. High performance fully etched isotropic microring resonators in thin-film lithium niobate on insulator platform. OPTICS EXPRESS 2019; 27:22025-22039. [PMID: 31510266 DOI: 10.1364/oe.27.022025] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
We present our design, fabrication, and experimental results for very high-performance isotropic microring resonators with small radii (∼ 30 µm) based on single-mode strip waveguides and transverse magnetic (TM) polarization in a fully etched lithium niobate (Z-cut) thin-film on insulator. The loss of the devices is predicted to be < 10 dB/cm, and is measured to be ∼ 7 dB/cm. The measured optical responses of microring resonators exhibit an extinction of ∼ 25 dB (close to critical coupling), a 3 dB optical bandwidth of 49 pm (∼ 6 GHz) for all-pass structures, an extinction of ∼ 10 dB for add-drop structures, and a free spectral range of ∼ 5.26 nm, all of which are in excellent agreement with the design. This work is the first step towards ultra-compact and fully isotropic optical modulators in thin-film lithium niobate on insulator.
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33
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Krasnokutska I, Chapman RJ, Tambasco JLJ, Peruzzo A. High coupling efficiency grating couplers on lithium niobate on insulator. OPTICS EXPRESS 2019; 27:17681-17685. [PMID: 31252724 DOI: 10.1364/oe.27.017681] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Accepted: 05/12/2019] [Indexed: 06/09/2023]
Abstract
We demonstrate monolithically defined grating couplers in Z-cut lithium niobate on insulator for efficient vertical coupling between an optical fiber and a single mode waveguide. The grating couplers exhibit ∼ 44.6%/coupler and ∼ 19.4%/coupler coupling efficiency for TE and TM polarized light respectively. Taperless grating couplers are investigated to realize a more compact design.
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34
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Krasnokutska I, Tambasco JLJ, Peruzzo A. Nanostructuring of LNOI for efficient edge coupling. OPTICS EXPRESS 2019; 27:16578-16585. [PMID: 31252882 DOI: 10.1364/oe.27.016578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Accepted: 04/10/2019] [Indexed: 06/09/2023]
Abstract
We present the design, fabrication and characterization of LNOI fiber-to-chip inverse tapers for efficient monolithic edge coupling. The etching characteristics of various LNOI crystal cuts are investigated for the realization of butt-coupling devices. We experimentally demonstrate that the crystal cut limits the performance of mode matching tapers studied in this work. We report a butt-coupling loss of 2.5±0.5 dB/facet across the C/L-band and 6 dB/facet (at 1550 nm) by implementing 200 nm tip mode matching tapers in +Z-cut LNOI and X-cut MgO:LNOI, respectively. We anticipate that these results will provide insight into the nanostructuring of LNOI and into the further development of efficient butt-coupling in this platform.
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35
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Kar A, Bahadori M, Gong S, Goddard LL. Realization of alignment-tolerant grating couplers for z-cut thin-film lithium niobate. OPTICS EXPRESS 2019; 27:15856-15867. [PMID: 31163775 DOI: 10.1364/oe.27.015856] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 05/12/2019] [Indexed: 06/09/2023]
Abstract
We present the design, modeling, fabrication, and characterization of grating coupler devices for z-cut lithium niobate near 1550 nm. We first experimentally measure the sensitivity of the insertion loss of a conventional grating coupler to translational misalignment through a three-factor full factorial design of experiment. Next, we design grating couplers that are significantly less sensitive to misalignment. The fabricated devices experienced less than 7 dB of excess insertion loss for combined misalignments of up to ± 5 μm in plane and up to -2 μm or + 10 μm out of plane.
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36
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He L, Zhang M, Shams-Ansari A, Zhu R, Wang C, Marko L. Low-loss fiber-to-chip interface for lithium niobate photonic integrated circuits. OPTICS LETTERS 2019; 44:2314-2317. [PMID: 31042212 DOI: 10.1364/ol.44.002314] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 04/05/2019] [Indexed: 06/09/2023]
Abstract
Integrated lithium niobate (LN) photonic circuits have recently emerged as a promising candidate for advanced photonic functions such as high-speed modulation, nonlinear frequency conversion, and frequency comb generation. For practical applications, optical interfaces that feature low fiber-to-chip coupling losses are essential. So far, the fiber-to-chip loss (commonly >10 dB/facet) has dominated the total insertion losses of typical LN photonic integrated circuits, where on-chip losses can be as low as 0.03-0.1 dB/cm. Here we experimentally demonstrate a low-loss mode size converter for coupling between a standard lensed fiber and sub-micrometer LN rib waveguides. The coupler consists of two inverse tapers that convert the small optical mode of a rib waveguide into a symmetrically guided mode of a LN nanowire, featuring a larger mode area matched to that of a tapered optical fiber. The measured fiber-to-chip coupling loss is lower than 1.7 dB/facet with high fabrication tolerance and repeatability. Our results open the door for practical integrated LN photonic circuits efficiently interfaced with optical fibers.
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37
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The Photorefractive Response of Zn and Mo Codoped LiNbO3 in the Visible Region. CRYSTALS 2019. [DOI: 10.3390/cryst9050228] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We mainly investigated the effect of the valence state of photorefractive resistant elements on the photorefractive properties of codoped crystals, taking the Zn and Mo codoped LiNbO3 (LN:Mo,Zn) crystal as an example. Especially, the response time and photorefractive sensitivity of 7.2 mol% Zn and 0.5 mol% Mo codoped with LiNbO3 (LN:Mo,Zn7.2) crystal are 0.65 s and 4.35 cm/J at 442 nm, respectively. The photorefractive properties of the LN:Mo,Zn crystal are similar to the Mg and Mo codoped LiNbO3 crystal, which are better than the Zr and Mo codoped LiNbO3 crystal. The results show that the valence state of photorefractive resistant ions is an important factor for the photorefractive properties of codoped crystals and that the LN:Mo,Zn7.2 crystal is another potential material with fast response to holographic storage.
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Cai L, Mahmoud A, Piazza G. Low-loss waveguides on Y-cut thin film lithium niobate: towards acousto-optic applications. OPTICS EXPRESS 2019; 27:9794-9802. [PMID: 31045128 DOI: 10.1364/oe.27.009794] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 03/13/2019] [Indexed: 06/09/2023]
Abstract
We investigate the dependence of photonic waveguide propagation loss on the thickness of the buried oxide layer in Y-cut lithium niobate on insulator substrate to identify trade-offs between optical losses and electromechanical coupling of surface acoustic wave (SAW) devices for acousto-optic applications. Simulations show that a thicker oxide layer reduces the waveguide loss but lowers the electromechanical coupling coefficient of the SAW device. Optical racetrack resonators with different lengths were fabricated by argon plasma etching to experimentally extract waveguide losses. By increasing the oxide layer thickness from 1 µm to 2 µm, we were able to reduce propagation loss of 2 µm (1 µm) wide waveguide from 1.85 dB/cm (3 dB/cm) to as low as 0.37 dB/cm (0.77 dB/cm). Resonators with a quality factor greater than 1 million were demonstrated as well. An oxide thickness of approximately 1.5 µm is sufficient to significantly reduce propagation loss, due to leakage into the substrate and simultaneously attain good electromechanical coupling in acoustic devices. This work not only provides insights on the design and realization of low-loss photonic waveguides in lithium niobate, but also, most importantly, offers experimental evidence of how the oxide thickness directly impacts losses and guides its selection for the synthesis of high-performance acousto-optic devices in Y-cut lithium niobate on insulator.
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Honardoost A, Juneghani FA, Safian R, Fathpour S. Towards subterahertz bandwidth ultracompact lithium niobate electrooptic modulators. OPTICS EXPRESS 2019; 27:6495-6501. [PMID: 30876233 DOI: 10.1364/oe.27.006495] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 02/16/2019] [Indexed: 06/09/2023]
Abstract
Achieving ultrahigh-speed electro-optic modulators (subterahertz modulation bandwidths) is shown to be feasible in the thin-film lithium niobate integrated photonic platform. Design guidelines for optimization of the main radio-frequency and optical parameters are presented, and 3-dB modulation bandwidth up to 400 GHz is proved attainable in 3-mm-long devices. Such unprecedented bandwidths pave the path towards utilizing the devices in advanced optical communication systems.
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40
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Gorelick S, de Marco A. Refractive micro-lenses and micro-axicons in single-crystal lithium niobate. OPTICS EXPRESS 2018; 26:32324-32331. [PMID: 30650693 DOI: 10.1364/oe.26.032324] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Accepted: 10/15/2018] [Indexed: 06/09/2023]
Abstract
The high refractive index of lithium niobate crystal (n = 2.2) and the highly transparent range (300-5000 nm), makes it a perfect material for refractive lenses and other types of micro-optical elements. This material already finds extensive use in waveguides and photonic crystals, however, little work has been done on producing refractive optical components in lithium niobate, presumably due to the challenges associated with its fragility and difficulties in three-dimensional micromachining. In this study, we fabricated high-quality refractive micro-lenses and micro-axicons with low surface roughness (< λvis / 20), with 220 µm diameters and sag heights up to 22 µm in single-crystal LN using focused Xe beam milling. Xe ion beam milling is a flexible and rapid technique allowing realization of complex three-dimensional surface reliefs directly in lithium niobate. We characterized the optical performance of the fabricated elements showing sub-µm focusing capabilities of both the lenses and axicons.
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41
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Jian J, Xu P, Chen H, He M, Wu Z, Zhou L, Liu L, Yang C, Yu S. High-efficiency hybrid amorphous silicon grating couplers for sub-micron-sized lithium niobate waveguides. OPTICS EXPRESS 2018; 26:29651-29658. [PMID: 30469926 DOI: 10.1364/oe.26.029651] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Accepted: 10/08/2018] [Indexed: 06/09/2023]
Abstract
We demonstrate hybrid amorphous silicon uniform grating couplers for efficient coupling between the standard single-mode fiber and sub-micron lithium niobate waveguides. The grating couplers exhibit coupling efficiency of -3.06 dB and 1-dB bandwidth of 55 nm. The amorphous silicon grating couplers can also provide a universal building block applicable to other photonic platforms such as silicon nitride waveguides, whose moderate refractive index values prevent high efficiency grating couplers to be fabricated in the native waveguide.
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Wu R, Wang M, Xu J, Qi J, Chu W, Fang Z, Zhang J, Zhou J, Qiao L, Chai Z, Lin J, Cheng Y. Long Low-Loss-Litium Niobate on Insulator Waveguides with Sub-Nanometer Surface Roughness. NANOMATERIALS 2018; 8:nano8110910. [PMID: 30404137 PMCID: PMC6265866 DOI: 10.3390/nano8110910] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Revised: 10/27/2018] [Accepted: 11/02/2018] [Indexed: 01/07/2023]
Abstract
In this paper, we develop a technique for realizing multi-centimeter-long lithium niobate on insulator (LNOI) waveguides with a propagation loss as low as 0.027 dB/cm. Our technique relies on patterning a chromium thin film coated on the top surface of LNOI into a hard mask with a femtosecond laser followed by chemo-mechanical polishing for structuring the LNOI into the waveguides. The surface roughness on the waveguides was determined with an atomic force microscope to be 0.452 nm. The approach is compatible with other surface patterning technologies, such as optical and electron beam lithographies or laser direct writing, enabling high-throughput manufacturing of large-scale LNOI-based photonic integrated circuits.
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Affiliation(s)
- Rongbo Wu
- State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China.
- University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Min Wang
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China.
- XXL-The Extreme Optoelectromechanics Laboratory, School of Physics and Materials Science, East China Normal University, Shanghai 200241, China.
| | - Jian Xu
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China.
- XXL-The Extreme Optoelectromechanics Laboratory, School of Physics and Materials Science, East China Normal University, Shanghai 200241, China.
| | - Jia Qi
- State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China.
- University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Wei Chu
- State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China.
- XXL-The Extreme Optoelectromechanics Laboratory, School of Physics and Materials Science, East China Normal University, Shanghai 200241, China.
| | - Zhiwei Fang
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China.
- XXL-The Extreme Optoelectromechanics Laboratory, School of Physics and Materials Science, East China Normal University, Shanghai 200241, China.
| | - Jianhao Zhang
- State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China.
- University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Junxia Zhou
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China.
- XXL-The Extreme Optoelectromechanics Laboratory, School of Physics and Materials Science, East China Normal University, Shanghai 200241, China.
| | - Lingling Qiao
- State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China.
| | - Zhifang Chai
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China.
- XXL-The Extreme Optoelectromechanics Laboratory, School of Physics and Materials Science, East China Normal University, Shanghai 200241, China.
| | - Jintian Lin
- State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China.
| | - Ya Cheng
- State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China.
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China.
- XXL-The Extreme Optoelectromechanics Laboratory, School of Physics and Materials Science, East China Normal University, Shanghai 200241, China.
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, Shanxi, China.
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He Y, Liang H, Luo R, Li M, Lin Q. Dispersion engineered high quality lithium niobate microring resonators. OPTICS EXPRESS 2018; 26:16315-16322. [PMID: 30119464 DOI: 10.1364/oe.26.016315] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Accepted: 06/07/2018] [Indexed: 06/08/2023]
Abstract
Lithium niobate (LN) exhibits outstanding material properties with great potential for many applications. Recent advance in LN integrated photonics on chip-scale platforms has shown significant advantages in device engineering and functionality innovation. Precise engineering of group-velocity dispersion (GVD) is crucial for many important nonlinear photonic applications. In this paper, we demonstrate high-Q LN microring resonators, with optical Q above 1 million, whose GVD can be flexibly controlled in both normal and anomalous dispersion regimes, with a value between -0.128 ps2/m and 0.043 ps2/m in the telecom band, by controlling the device cross section and by utilizing the birefringence. We are able to achieve a small anomalous GVD of -0.015 ps2/m that is even smaller than that of a silica optical fiber. The flexible engineering of GVD paves a critical step towards broad nonlinear photonic applications in high-Q LN microring resonators.
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Mercante AJ, Shi S, Yao P, Xie L, Weikle RM, Prather DW. Thin film lithium niobate electro-optic modulator with terahertz operating bandwidth. OPTICS EXPRESS 2018; 26:14810-14816. [PMID: 29877417 DOI: 10.1364/oe.26.014810] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
We present a thin film crystal ion sliced (CIS) LiNbO3 phase modulator that demonstrates an unprecedented measured electro-optic (EO) response up to 500 GHz. Shallow rib waveguides are utilized for guiding a single transverse electric (TE) optical mode, and Au coplanar waveguides (CPWs) support the modulating radio frequency (RF) mode. Precise index matching between the co-propagating RF and optical modes is responsible for the device's broadband response, which is estimated to extend even beyond 500 GHz. Matching the velocities of these co-propagating RF and optical modes is realized by cladding the modulator's interaction region in a thin UV15 polymer layer, which increases the RF modal index. The fabricated modulator possesses a tightly confined optical mode, which lends itself to a strong interaction between the modulating RF field and the guided optical carrier; resulting in a measured DC half-wave voltage of 3.8 V·cm-1. The design, fabrication, and characterization of our broadband modulator is presented in this work.
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45
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