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Wang H, Zuo Y, Yin X, Chen Z, Zhang Z, Wang F, Hu Y, Zhang X, Peng C. Ultralow-loss optical interconnect enabled by topological unidirectional guided resonance. SCIENCE ADVANCES 2024; 10:eadn4372. [PMID: 38507487 PMCID: PMC10954227 DOI: 10.1126/sciadv.adn4372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2023] [Accepted: 02/12/2024] [Indexed: 03/22/2024]
Abstract
Grating couplers that interconnect photonic chips to off-chip components are crucial for various optoelectronics applications. Despite numerous efforts in past decades, the existing grating couplers are still far from optimal in energy efficiency and thus hinder photonic integration toward a larger scale. Here, we propose a strategy to achieve ultralow-loss grating couplers by using unidirectional guided resonances (UGRs), suppressing the useless downward radiation with no mirror on the bottom. By engineering the dispersion and apodizing the geometry of grating, we experimentally realize a grating coupler with a record-low loss of -0.34 dB and 1-dB bandwidth exceeding 30 nm at the telecom wavelength of 1550 nm and further demonstrate an optic via with a loss of only -0.94 dB. Given that UGRs ubiquitously exist in a variety of grating geometries, our work sheds light on a systematic method to achieve energy-efficient optical interconnect and paves the way to large-scale photonic integration.
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Affiliation(s)
- Haoran Wang
- State Key Laboratory of Advanced Optical Communication Systems and Networks, Department of Electronics & Frontiers Science Center for Nano-optoelectronics, Peking University, Beijing 100871, China
| | - Yi Zuo
- State Key Laboratory of Advanced Optical Communication Systems and Networks, Department of Electronics & Frontiers Science Center for Nano-optoelectronics, Peking University, Beijing 100871, China
| | - Xuefan Yin
- State Key Laboratory of Advanced Optical Communication Systems and Networks, Department of Electronics & Frontiers Science Center for Nano-optoelectronics, Peking University, Beijing 100871, China
- Department of Electronic Science and Engineering, Kyoto University, Kyoto-Daigaku-Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Zihao Chen
- State Key Laboratory of Advanced Optical Communication Systems and Networks, Department of Electronics & Frontiers Science Center for Nano-optoelectronics, Peking University, Beijing 100871, China
| | - Zixuan Zhang
- State Key Laboratory of Advanced Optical Communication Systems and Networks, Department of Electronics & Frontiers Science Center for Nano-optoelectronics, Peking University, Beijing 100871, China
| | - Feifan Wang
- State Key Laboratory of Advanced Optical Communication Systems and Networks, Department of Electronics & Frontiers Science Center for Nano-optoelectronics, Peking University, Beijing 100871, China
| | - Yuefeng Hu
- Peng Cheng Laboratory, Shenzhen 518055, China
- Peking University Shenzhen Graduate School, Shenzhen 518055, China
| | - Xiaoyu Zhang
- State Key Laboratory of Advanced Optical Communication Systems and Networks, Department of Electronics & Frontiers Science Center for Nano-optoelectronics, Peking University, Beijing 100871, China
| | - Chao Peng
- State Key Laboratory of Advanced Optical Communication Systems and Networks, Department of Electronics & Frontiers Science Center for Nano-optoelectronics, Peking University, Beijing 100871, China
- Peng Cheng Laboratory, Shenzhen 518055, China
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Hansen SE, Arregui G, Babar AN, Albrechtsen M, Vosoughi Lahijani B, Christiansen RE, Stobbe S. Efficient low-reflection fully etched vertical free-space grating couplers for suspended silicon photonics. OPTICS EXPRESS 2023; 31:17424-17436. [PMID: 37381477 DOI: 10.1364/oe.485356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Accepted: 04/27/2023] [Indexed: 06/30/2023]
Abstract
We design and fabricate a grating coupler for interfacing suspended silicon photonic membranes with free-space optics while being compatible with single-step lithography and etching in 220 nm silicon device layers. The grating coupler design simultaneously and explicitly targets both high transmission into a silicon waveguide and low reflection back into the waveguide by means of a combination of a two-dimensional shape-optimization step followed by a three-dimensional parameterized extrusion. The designed coupler has a transmission of -6.6 dB (21.8 %), a 3 dB bandwidth of 75 nm, and a reflection of -27 dB (0.2 %). We experimentally validate the design by fabricating and optically characterizing a set of devices that allow the subtraction of all other sources of transmission losses as well as the inference of back-reflections from Fabry-Pérot fringes, and we measure a transmission of 19 % ± 2 %, a bandwidth of 65 nm and a reflection of 1.0 % ± 0.8 %.
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3
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Kashi AA, van der Tol JJGM, Williams KA, Jiao Y. Efficient and fabrication error tolerant grating couplers on the InP membrane on silicon platform. APPLIED OPTICS 2022; 61:9926-9936. [PMID: 36606824 DOI: 10.1364/ao.473271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 10/24/2022] [Indexed: 06/17/2023]
Abstract
In order to couple light between photonic integrated circuits and optical fibers, grating couplers are commonly employed. This paper describes the design and fabrication of deep and shallow-etched grating couplers with a metal back-reflector with record low insertion losses in InP-based platforms. The measured insertion losses for deep and shallow-etched gratings are 2.4 and 2.6 dB, respectively. Additionally, fabrication error tolerances in shallow etched grating couplers have been examined experimentally, which showed high tolerance of this structure toward the grating period and fill factor.
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4
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Chen S, Ourari S, Raha M, Phenicie CM, Uysal MT, Thompson JD. Hybrid microwave-optical scanning probe for addressing solid-state spins in nanophotonic cavities. OPTICS EXPRESS 2021; 29:4902-4911. [PMID: 33726036 DOI: 10.1364/oe.417528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 01/23/2021] [Indexed: 06/12/2023]
Abstract
Spin-photon interfaces based on solid-state atomic defects have enabled a variety of key applications in quantum information processing. To maximize the light-matter coupling strength, defects are often placed inside nanoscale devices. Efficiently coupling light and microwave radiation into these structures is an experimental challenge, especially in cryogenic or high vacuum environments with limited sample access. In this work, we demonstrate a fiber-based scanning probe that simultaneously couples light into a planar photonic circuit and delivers high power microwaves for driving electron spin transitions. The optical portion achieves 46% one-way coupling efficiency, while the microwave portion supplies an AC magnetic field with strength up to 9 Gauss at 10 Watts of input microwave power. The entire probe can be scanned across a large number of devices inside a 3He cryostat without free-space optical access. We demonstrate this technique with silicon nanophotonic circuits coupled to single Er3+ ions.
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Li S, Cai L, Gao D, Dong J, Hou J, Yang C, Chen S, Zhang X. Deterministic design of focusing apodized subwavelength grating coupler based on weak form and transformation optics. OPTICS EXPRESS 2020; 28:35395-35412. [PMID: 33182986 DOI: 10.1364/oe.409981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 10/29/2020] [Indexed: 06/11/2023]
Abstract
The focusing apodized subwavelength grating coupler (F-ASGC) has advantages of high coupling efficiency, small footprint and simple fabrication process, which make it a popular component for chip-scale coupling and testing of integrated optical circuit. However, the design of F-ASGC based on effective medium theory lacks accuracy, causing the drawbacks of peak wavelength deviation and performance degradation. In this work, we propose a deterministic design method of F-ASGC. Our grating coupler is formed by assembling various subwavelength grating units according to their complex effective indexes. The complex effective indexes of these grating units are accurately obtained by the weak form calculation. Then combining with transformation optics, we strictly analyze the F-ASGC for the first time. The simulation results show that the deterministically designed F-ASGC has high coupling efficiency of -2.51 dB, 3 dB bandwidth of 51 nm, and accurate central wavelength of 1553.1 nm. And we also fabricated it on the commercial SOI wafer. The measured maximum efficiency is -3.10 dB, the 3 dB bandwidth is 55 nm, and the central wavelength is 1551.5 nm.
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Chen S, Raha M, Phenicie CM, Ourari S, Thompson JD. Parallel single-shot measurement and coherent control of solid-state spins below the diffraction limit. Science 2020; 370:592-595. [DOI: 10.1126/science.abc7821] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 09/11/2020] [Indexed: 11/02/2022]
Affiliation(s)
- Songtao Chen
- Department of Electrical Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Mouktik Raha
- Department of Electrical Engineering, Princeton University, Princeton, NJ 08544, USA
| | | | - Salim Ourari
- Department of Electrical Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Jeff D. Thompson
- Department of Electrical Engineering, Princeton University, Princeton, NJ 08544, USA
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Johnson M, Thompson MG, Sahin D. Low-loss, low-crosstalk waveguide crossing for scalable integrated silicon photonics applications. OPTICS EXPRESS 2020; 28:12498-12507. [PMID: 32403746 DOI: 10.1364/oe.381304] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 02/19/2020] [Indexed: 06/11/2023]
Abstract
A waveguide crossing based on multi-mode interference is designed and experimentally characterized on the silicon platform. The insertion loss of the device is measured as 43 ± 4 mdB per crossing, with a crosstalk of < -50 dB between 1550 and 1560 nm, in good agreement with predictions from 3D finite-difference time-domain simulations. Furthermore, the device backscatter was investigated using white light reflectometry and no significant backscatter was observed from 160 waveguide crossings in the time domain. In the frequency domain, the backscatter of the waveguide crossing device was measured experimentally for the first time, achieving a backscatter of -55 dB. The crossing has a footprint of 14.3 x 14.3 µm2 and can be fabricated in a single step.
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Khan M, Bain JA, Piazza G. Efficient arsenic trisulfide vertical grating coupler on lithium niobate for integrated photonic applications. OPTICS LETTERS 2019; 44:4558-4561. [PMID: 31517930 DOI: 10.1364/ol.44.004558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 08/17/2019] [Indexed: 06/10/2023]
Abstract
An efficient vertical grating coupler design for arsenic trisulfide (As2S3) on silicon dioxide (SiO2) on lithium niobate (LN) is proposed, fabricated, and experimentally verified. We report 4 dB coupling efficiency per grating for vertical fiber coupling at a wavelength of 1550 nm with a 3 dB bandwidth of 40 nm using an aluminum reflector mirror between the LN and SiO2 interface. This coupler is the first step towards the demonstration of high-performance integrated photonic devices, which would simultaneously benefit from the acousto-optic properties of As2S3 and electro-optic and acoustic properties of LN. This hybrid platform is deemed to impact a broad range of applications such as imaging, ranging, and inertial sensing.
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A high efficiency silicon nitride waveguide grating coupler with a multilayer bottom reflector. Sci Rep 2019; 9:12988. [PMID: 31506482 PMCID: PMC6736935 DOI: 10.1038/s41598-019-49324-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Accepted: 08/14/2019] [Indexed: 11/09/2022] Open
Abstract
We propose a high efficiency apodized grating coupler with a bottom reflector for silicon nitride photonic integrated circuits. The reflector consists of a stack of alternate silicon nitride and silicon dioxide quarter-wave films. The design, fabrication and optical characterization of the couplers has been presented. The measured fiber to detector insertion loss was −3.5 dB which corresponds to a peak coupling efficiency of −1.75 dB. A 3 dB wavelength bandwidth of 76.34 nm was demonstrated for the grating coupler with a 20-layer reflector. The fabrication process is CMOS-compatible and requires only a single etching step.
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Xue Y, Chen H, Bao Y, Dong J, Zhang X. Two-dimensional silicon photonic grating coupler with low polarization-dependent loss and high tolerance. OPTICS EXPRESS 2019; 27:22268-22274. [PMID: 31510523 DOI: 10.1364/oe.27.022268] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 07/08/2019] [Indexed: 06/10/2023]
Abstract
We design and demonstrate a two-dimensional grating coupler with an elliptical-like etching pattern on the silicon-on-insulator platform. The polarization-dependent loss of the fabricated device is measured to be 0.2 dB at the C-band, lower than that of most conventional 2D GCs. The etching unit can be easily fabricated with a large tolerance of ± 10 nm and a large feature size of 310nm, which is beneficial to its manufacturing process and wide application.
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11
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Xu L, Wang Y, Mao D, El-Fiky E, Xing Z, Kumar A, Saber MG, Jacques M, Plant DV. Broadband 1310/1550 nm wavelength demultiplexer based on a multimode interference coupler with tapered internal photonic crystal for the silicon-on-insulator platform. OPTICS LETTERS 2019; 44:1770-1773. [PMID: 30933143 DOI: 10.1364/ol.44.001770] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Accepted: 03/07/2019] [Indexed: 06/09/2023]
Abstract
We design and experimentally demonstrate a broadband 1310/1550 nm wavelength demultiplexer based on a multimode interference coupler with a tapered internal photonic crystal (PC) structure for the silicon-on-insulator platform. The tapered internal PC structure is engineered to reflect the C-band light while transmitting the O-band light. Novel PC nanotapers are introduced for the internal PC structure that effectively suppress the sidelobe of the photonic bandgap and enable our device to be operable over the O-band. The device was fabricated using electron beam lithography, and its performance has been experimentally characterized. The measured extinction ratios are higher than 15 dB over a 74 nm bandwidth from 1286 to 1360 nm at the O-band, and over a 103 nm bandwidth from 1527 to 1630 nm that covers the C-band and the L-band.
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12
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Zeng YS, Qu SW, Wang C, Chen BJ, Chan C. Efficient unidirectional and broadband vertical-emitting optical coupler assisted by aperture-coupled nanopatch antenna array. OPTICS EXPRESS 2019; 27:9941-9954. [PMID: 31045142 DOI: 10.1364/oe.27.009941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Accepted: 03/11/2019] [Indexed: 06/09/2023]
Abstract
Vertical-emitting optical couplers that convert in-plane guided light to out-of-plane emission are crucial elements for future photonic integrated circuits. However, traditional vertical-coupling elements, such as grating couplers, by default radiate light in both upward and downward directions, leading to a significant reduction of device efficiency. In this paper, we propose to solve this problem using a novel nanopatch antenna array, inspired by patch antenna theories commonly deployed in microwave circuits. The proposed nanopatch array features an up-to-down emission directionality up to 12.91 dBc and a wide operating bandwidth of over 400 nm simultaneously. Compared with a typical waveguide grating antenna, our design shows a significantly higher free-space gain of 24.27 dBi. The unidirectional, efficient, and broadband antenna arrays presented here are promising for a range of integrated photonics applications, including inter-chip photonic interconnects, light ranging and detection, optical communications, and biological imaging.
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13
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Guan X, Frandsen LH. All-silicon interferometer with multimode waveguides for temperature-insensitive filters and compact biosensors. OPTICS EXPRESS 2019; 27:753-760. [PMID: 30696156 DOI: 10.1364/oe.27.000753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Accepted: 12/11/2018] [Indexed: 06/09/2023]
Abstract
We report a novel design of an all-silicon temperature-independent filter employing a Mach-Zehnder interferometer (MZI) with multimode waveguides. The two arms of the MZI have equal lengths and equal widths but propagate different modes having different effective indices to guarantee an optical path difference (OPD) but similar temperature-dependence to diminish any thermal shifts of the interference pattern. A temperature-independent MZI filter with only one channel is also proposed and experimentally demonstrated. Measurements verify the principle of operation and a low temperature sensitivity of -20 to 10 pm/°C in the C-band for both MZI filters is achieved. The one-channel MZI structure is furthermore employed to achieve a compact sensor exhibiting a high sensitivity of 826 nm/RIU (refractive index unit).
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14
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Ong EW, Wallner T, Fahrenkopf NM, Coolbaugh DD. High positional freedom SOI subwavelength grating coupler (SWG) for 300 mm foundry fabrication. OPTICS EXPRESS 2018; 26:28773-28792. [PMID: 30470049 DOI: 10.1364/oe.26.028773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Accepted: 08/27/2018] [Indexed: 06/09/2023]
Abstract
We present an apodized, single etch-step, subwavelength grating (SWG) high positional freedom (HPF) grating coupler based on the 220 nm silicon-on-insulator (SOI) with 2μm BOX substrate. The grating coupler was designed for 1550 nm light with transverse electric (TE) polarization. It has a measured maximum coupling efficiency of -7.49 dB (17.8%) and a -1 dB/-3 dB bandwidth of ~14 nm/29.5 nm respectively. It was fabricated in a 300mm state of the art CMOS foundry. This work presents an SOI-based grating coupler with the highest-to the best of our knowledge- -1 dB single mode fiber lateral alignment of 21.4 μm × 10.1 μm.
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15
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Kim S, Westly DA, Roxworthy BJ, Li Q, Yulaev A, Srinivasan K, Aksyuk VA. Photonic waveguide to free-space Gaussian beam extreme mode converter. LIGHT, SCIENCE & APPLICATIONS 2018; 7:72. [PMID: 30323924 PMCID: PMC6177431 DOI: 10.1038/s41377-018-0073-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Revised: 09/06/2018] [Accepted: 09/10/2018] [Indexed: 05/10/2023]
Abstract
Integration of photonic chips with millimeter-scale atomic, micromechanical, chemical, and biological systems can advance science and enable new miniaturized hybrid devices and technology. Optical interaction via small evanescent volumes restricts performance in applications such as gas spectroscopy, and a general ability to photonically access optical fields in large free-space volumes is desired. However, conventional inverse tapers and grating couplers do not directly scale to create wide, high-quality collimated beams for low-loss diffraction-free propagation over many millimeters in free space, necessitating additional bulky collimating optics and expensive alignment. Here, we develop an extreme mode converter, which is a compact planar photonic structure that efficiently couples a 300 nm × 250 nm silicon nitride high-index single-mode waveguide to a well-collimated near surface-normal Gaussian beam with an ≈160 µm waist, which corresponds to an increase in the modal area by a factor of >105. The beam quality is thoroughly characterized, and propagation over 4 mm in free space and coupling back into a single-mode photonic waveguide with low loss via a separate identical mode converter is demonstrated. To achieve low phase error over a beam area that is >100× larger than that of a typical grating coupler, our approach separates the two-dimensional mode expansion into two sequential separately optimized stages, which create a fully expanded and well-collimated Gaussian slab mode before out-coupling it into free space. Developed at 780 nm for integration with chip-scale atomic vapor cell cavities, our design can be adapted for visible, telecommunication, or other wavelengths. The technique can be expanded to more arbitrary phase and intensity control of both large-diameter, free-space optical beams and wide photonic slab modes.
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Affiliation(s)
- Sangsik Kim
- Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899 USA
- Maryland Nanocenter, University of Maryland, College Park, MD 20742 USA
- Department of Electrical and Computer Engineering, Texas Tech University, Lubbock, TX 79409 USA
| | - Daron A. Westly
- Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899 USA
| | - Brian J. Roxworthy
- Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899 USA
| | - Qing Li
- Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899 USA
- Maryland Nanocenter, University of Maryland, College Park, MD 20742 USA
| | - Alexander Yulaev
- Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899 USA
- Maryland Nanocenter, University of Maryland, College Park, MD 20742 USA
| | - Kartik Srinivasan
- Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899 USA
| | - Vladimir A. Aksyuk
- Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899 USA
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Experimentally validated full-vectorial model of wavelength multicasting via four-wave mixing in straight waveguides. Sci Rep 2018; 8:13030. [PMID: 30158626 PMCID: PMC6115365 DOI: 10.1038/s41598-018-31470-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 08/20/2018] [Indexed: 11/24/2022] Open
Abstract
We derive full-vectorial nonlinear propagation equations of dual-pumped four-wave mixing in straight waveguides, which are valid in characterizing the one-to-six wavelength multicasting. Special attention is paid to the resulting idler wavelengths and their conversion efficiency, which enables the optimization of the experimental designs, including the incident wavelength and the power of pumps and signal. We validate the model by comparing the numerical simulation to the experimental measurement in a silicon-on-insulator waveguide, for the first time to our best knowledge, and achieve a good agreement. We further derive the general form of the proposed model for the case of using multiple,pumps, which holds a potential to numerically predict the performance of complex wavelength multicasting, and essentially guide the waveguide designs.
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Hong J, Qiu F, Spring AM, Yokoyama S. Silicon waveguide grating coupler based on a segmented grating structure. APPLIED OPTICS 2018; 57:3301-3305. [PMID: 29714320 DOI: 10.1364/ao.57.003301] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 03/23/2018] [Indexed: 06/08/2023]
Abstract
We present the simulation, fabrication, and experimental results of a high-efficiency and wide-bandwidth segmented waveguide grating coupler on a silicon-on-insulator platform for near vertical optical coupling between the waveguide and optical fiber. The coupler comprises segmented gratings, which can increase vertical coupling to the optical fiber and reduce backward reflection. The proposed grating coupler has a 3 dB bandwidth of 71.4 nm and a coupling efficiency of 51.7% at a wavelength of 1550 nm. Compared with the standard uniform waveguide grating coupler, the coupling efficiency was improved by 25.64%.
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18
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A compact silicon grating coupler based on hollow tapered spot-size converter. Sci Rep 2018; 8:2540. [PMID: 29416080 PMCID: PMC5803240 DOI: 10.1038/s41598-018-20875-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 01/18/2018] [Indexed: 12/02/2022] Open
Abstract
A new compact silicon grating coupler enabling fibre-to-chip light coupling at a minimized taper length is proposed. The proposed coupler, which incorporates a hollow tapered waveguide, converts the spot-size of optical modes from micro- to nano-scales by reducing the lateral dimension from 15 µm to 300 nm at a length equals to 60 µm. The incorporation of such a coupler in photonic integrated circuit causes a physical footprint as small as 81 µm × 15 µm with coupling efficiency and 3-dB coupling bandwidth as high as 72% and 69 nm respectively.
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Du J, Wang J. Chip-scale optical vortex lattice generator on a silicon platform. OPTICS LETTERS 2017; 42:5054-5057. [PMID: 29216178 DOI: 10.1364/ol.42.005054] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 11/01/2017] [Indexed: 06/07/2023]
Abstract
An optical vortex (OV) with an isolated field singularity has been extensively studied in a variety of fields. An OV lattice with a network of optical vortices may find more advanced applications in widespread areas such as optical metrology, optical manipulation, and quantum processing. An OV lattice generated by traditional approaches relies on a number of bulky diffractive optical elements with large volumes and long working distances. Here we present a simple and compact on-chip OV lattice emitter on silicon photonics platforms. The principle relies on three-plane-wave interference. We design, fabricate, and demonstrate an on-chip OV lattice emitter consisting of three parallel waveguides with etched tilt gratings. The tilt gratings facilitate flexible light emission in a wide range of directions, enabling the generation of an OV lattice above the silicon chip. The demonstrated on-chip OV lattice emitter may open a door to generate, manipulate, and detect an OV lattice using photonic integrated circuits.
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High-efficiency grating-couplers: demonstration of a new design strategy. Sci Rep 2017; 7:16670. [PMID: 29192215 PMCID: PMC5709428 DOI: 10.1038/s41598-017-16505-z] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 11/13/2017] [Indexed: 11/24/2022] Open
Abstract
We present a simple and practical strategy that allows to design high-efficiency grating couplers. The technique is based on the simultaneous apodization of two structural parameters: the grating period and the fill-factor, along with the optimization of the grating coupler etching depth. Considering a 260 nm Si-thick Silicon-on-insulator platform, we numerically demonstrated a coupling efficiency of −0.8 dB (83%), well matching the experimental value of −0.9 dB (81%). Thanks to the optimized design, these results represent the best performance ever reported in the literature for SOI structures without the use of any back-reflector.
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21
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Ding Y, Guan X, Zhu X, Hu H, Bozhevolnyi SI, Oxenløwe LK, Jin KJ, Mortensen NA, Xiao S. Efficient electro-optic modulation in low-loss graphene-plasmonic slot waveguides. NANOSCALE 2017; 9:15576-15581. [PMID: 28984878 DOI: 10.1039/c7nr05994a] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Surface plasmon polaritons enable light concentration within subwavelength regions, opening thereby new avenues for miniaturizing the device and strengthening light-matter interactions. Here we realize efficient electro-optic modulation in low-loss plasmonic waveguides with the aid of graphene, and the devices are fully integrated in the silicon-on-insulator platform. By advantageously exploiting low-loss plasmonic slot-waveguide modes, which weakly leak into a substrate while featuring strong fields within the two-layer-graphene covered slots in metals, we successfully achieve a tunability of 0.13 dB μm-1 for our fabricated graphene-plasmonic waveguide devices with extremely low insertion loss, which outperforms previously reported graphene-plasmonic devices. Our results highlight the potential of graphene plasmonic leaky-mode hybrid waveguides to realize active ultra-compact devices for optoelectronic applications.
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Affiliation(s)
- Y Ding
- Department of Photonics Engineering, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark.
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Bacco D, Ding Y, Dalgaard K, Rottwitt K, Oxenløwe LK. Space division multiplexing chip-to-chip quantum key distribution. Sci Rep 2017; 7:12459. [PMID: 28963480 PMCID: PMC5622211 DOI: 10.1038/s41598-017-12309-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 09/07/2017] [Indexed: 12/04/2022] Open
Abstract
Quantum cryptography is set to become a key technology for future secure communications. However, to get maximum benefit in communication networks, transmission links will need to be shared among several quantum keys for several independent users. Such links will enable switching in quantum network nodes of the quantum keys to their respective destinations. In this paper we present an experimental demonstration of a photonic integrated silicon chip quantum key distribution protocols based on space division multiplexing (SDM), through multicore fiber technology. Parallel and independent quantum keys are obtained, which are useful in crypto-systems and future quantum network.
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Affiliation(s)
- Davide Bacco
- Technical University of Denmark, Department of Photonics Engineering, 2800, Kgs. Lyngby, Denmark.
| | - Yunhong Ding
- Technical University of Denmark, Department of Photonics Engineering, 2800, Kgs. Lyngby, Denmark.
| | - Kjeld Dalgaard
- Technical University of Denmark, Department of Photonics Engineering, 2800, Kgs. Lyngby, Denmark
| | - Karsten Rottwitt
- Technical University of Denmark, Department of Photonics Engineering, 2800, Kgs. Lyngby, Denmark
| | - Leif Katsuo Oxenløwe
- Technical University of Denmark, Department of Photonics Engineering, 2800, Kgs. Lyngby, Denmark
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23
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Guo K, Friis SMM, Christensen JB, Christensen EN, Shi X, Ding Y, Ou H, Rottwitt K. Full-vectorial propagation model and modified effective mode area of four-wave mixing in straight waveguides. OPTICS LETTERS 2017; 42:3670-3673. [PMID: 28914929 DOI: 10.1364/ol.42.003670] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Accepted: 08/19/2017] [Indexed: 06/07/2023]
Abstract
We derive from Maxwell's equations full-vectorial nonlinear propagation equations of four-wave mixing valid in straight semiconductor-on-insulator waveguides. Special attention is given to the resulting effective mode area, which takes a convenient form known from studies in photonic crystal fibers, but has not been introduced in the context of integrated waveguides. We show that the difference between our full-vectorial effective mode area and the scalar equivalent often referred to in the literature may lead to mistakes when evaluating the nonlinear refractive index and optimizing designs of new waveguides. We verify the results of our derivation by comparing it to experimental measurements in a silicon-on-insulator waveguide, taking tolerances on fabrication parameters into account.
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24
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Lai Y, Yu Y, Fu S, Xu J, Shum PP, Zhang X. Efficient spot size converter for higher-order mode fiber-chip coupling. OPTICS LETTERS 2017; 42:3702-3705. [PMID: 28914937 DOI: 10.1364/ol.42.003702] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 08/21/2017] [Indexed: 06/07/2023]
Abstract
We propose and demonstrate a silicon-based spot size converter (SSC), composed of two identical tapered channel waveguides and a Y-junction. The SSC is designed for first-order mode fiber-to-chip coupling on the basis of mode petal separation and the recombination method. Compared with a traditional on-chip SSC, this method is superior with reduced coupling loss when dealing with a higher-order mode. To the best of our knowledge, we present the first experimental observations of a higher-order SSC which is fully compatible with a standard fabrication process. Average coupling losses of 3 and 5.5 dB are predicted by simulation and demonstrated experimentally. A fully covered 3 dB bandwidth over a 1515-1585 nm wavelength range is experimentally observed.
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25
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Lu L, Zhang M, Zhou F, Chang W, Tang J, Li D, Ren X, Pan Z, Cheng M, Liu D. Inverse-designed ultra-compact star-crossings based on PhC-like subwavelength structures for optical intercross connect. OPTICS EXPRESS 2017; 25:18355-18364. [PMID: 28789322 DOI: 10.1364/oe.25.018355] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 07/17/2017] [Indexed: 06/07/2023]
Abstract
With the development of highly densified photonic integrated circuits, the optical cross nodes number exhibits dramatically increasing. Not only efficient but also ultra-compact waveguide crossings are required to materialize the full potential of silicon photonics for on-chip optical intercross connect. In this work, we proposed several inverse-designed 4 × 4, 5 × 5 and 6 × 6 star-crossings based on the photonic-crystal-like (PhC-like) subwavelength structures, which have ultra-high port density of about 7.1 μm2/port, 5.83 μm2/port and 7.3 μm2/port respectively. Moreover, the star-crossings are practically fabricated and experimentally characterized. The average measured insertion losses (ILs) are less than 0.75, 0.9 dB and 1.5 dB, while the crosstalks are sub-22.5 dB, -20 dB and -18 dB for other output ports over 60 nm bandwidth centered at 1550 nm wavelength.
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26
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Liu B, Zhang Y, He Y, Jiang X, Peng J, Qiu C, Su Y. Silicon photonic bandpass filter based on apodized subwavelength grating with high suppression ratio and short coupling length. OPTICS EXPRESS 2017; 25:11359-11364. [PMID: 28788818 DOI: 10.1364/oe.25.011359] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
A compact silicon bandpass filter with high sidelobe suppression is proposed and experimentally demonstrated using an apodized subwavelength grating (SWG) coupler. The device is implemented by placing a SWG waveguide next to a strip waveguide, and apodization is employed with a Gaussian profile to taper the gap between the two waveguides. A high sidelobe suppression ratio of 27 dB can be obtained with a 3-dB bandwidth of 8.8 nm and an insertion loss of 2.5 dB. Owing to the large optical phase mismatch between the two waveguides and the presence of the SWG waveguide, the coupling length of the device is reduced to 100.3 μm. The experimental results validate our proposed apodized-SWG-based contradirectional coupler (contra-DC) as a promising device in suppressing out-of-band components in coarse wavelength division multiplexed (CWDM) optical communication systems.
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27
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Yan S, Cheng Z, Frandsen LH, Ding Y, Zhou F, Dong J, Zhang X. Bandwidth-adaptable silicon photonic differentiator employing a slow light effect. OPTICS LETTERS 2017; 42:1596-1599. [PMID: 28409807 DOI: 10.1364/ol.42.001596] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
A photonic differentiator (DIFF) plays a crucial role in photonic circuits. Despite the fact that a DIFF having a terahertz bandwidth has been reported, the practical bandwidth is limited to being a bandpass response. In this Letter, we propose the concept of a bandwidth-adaptable DIFF, which exploits the slow light effect in a photonic crystal waveguide (PhCW) to overcome the inherent bandwidth limitation of current photonic DIFFs. We fabricated a PhCW Mach-Zehnder interferometer (PhCW-MZI) on the silicon-on-isolator material platform to validate our concept. Input Gaussian pulses with full width to half-maximums (FWHMs) ranging from 2.7 to 81.4 ps are accurately differentiated using our PhCW-MZI. Our all-passive scheme circumvents the bandwidth bottlenecks of previously reported photonic DIFFs and can greatly broaden the application area of photonic DIFFs.
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28
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Li S, Yu W, Meriggi L, Xiao Q, Nong Z, Cai X, Sorel M, Yu S. High-directional vortex beam emitter based on Archimedean spiral adiabatic waveguides. OPTICS LETTERS 2017; 42:975-978. [PMID: 28248345 DOI: 10.1364/ol.42.000975] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Integrated devices that emit light beams with orbital angular momentum (OAM) are becoming key components for wide-ranging applications. Here we propose and demonstrate a highly directional silicon photonic vortex beam emitter based on a 3-turn Archimedean spiral adiabatic waveguide integrated with an angular grating. Such a compact emitter is capable of generating vortex beams with small divergence angles and high directivity. Various orders of OAM modes can be selectively generated by the emitter at different wavelengths with a side-mode suppression ratio as large as 13.6 dB.
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29
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Qiu Y, Li X, Luo M, Chen D, Wang J, Xu J, Yang Q, Yu S. Mode-selective wavelength conversion of OFDM-QPSK signals in a multimode silicon waveguide. OPTICS EXPRESS 2017; 25:4493-4499. [PMID: 28241651 DOI: 10.1364/oe.25.004493] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We experimentally demonstrate on-chip mode-selective wavelength conversions based on the degenerate four-wave mixing (FWM) nonlinear effect in a few-mode silicon waveguide. A multimode waveguide with tapered directional coupler based mode (de)multiplexers is designed and fabricated. Using signals with advanced modulation formats all-optical wavelength conversions of 102.6-Gb/s OFDM-QPSK signals are verified. Experimental results show that only small optical signal-to-noise ratio (OSNR) penalties are observed after wavelength conversion of both modes, which are less than 2 dB for OFDM-QPSK at 7% forward error correction (FEC) threshold.
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30
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Slow-light-enhanced energy efficiency for graphene microheaters on silicon photonic crystal waveguides. Nat Commun 2017; 8:14411. [PMID: 28181531 PMCID: PMC5309776 DOI: 10.1038/ncomms14411] [Citation(s) in RCA: 124] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 12/24/2016] [Indexed: 12/22/2022] Open
Abstract
Slow light has been widely utilized to obtain enhanced nonlinearities, enhanced spontaneous emissions and increased phase shifts owing to its ability to promote light–matter interactions. By incorporating a graphene on a slow-light silicon photonic crystal waveguide, here we experimentally demonstrate an energy-efficient graphene microheater with a tuning efficiency of 1.07 nmmW−1 and power consumption per free spectral range of 3.99 mW. The rise and decay times (10–90%) are only 750 and 525 ns, which, to the best of our knowledge, are the fastest reported response times for microheaters in silicon photonics. The corresponding figure of merit of the device is 2.543 nW s, one order of magnitude better than results reported in previous studies. The influence of the length and shape of the graphene heater to the tuning efficiency is further investigated, providing valuable guidelines for enhancing the tuning efficiency of the graphene microheater. Slow light can be used to sustain strong light–matter interaction in silicon photonics. Here, the authors combine graphene with a silicon slow-light photonic crystal waveguide, demonstrating a fast and energy-efficient graphene microheater.
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31
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Liao S, Ding Y, Dong J, Yan S, Wang X, Zhang X. Photonic arbitrary waveform generator based on Taylor synthesis method. OPTICS EXPRESS 2016; 24:24390-24400. [PMID: 27828168 DOI: 10.1364/oe.24.024390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Arbitrary waveform generation has been widely used in optical communication, radar system and many other applications. We propose and experimentally demonstrate a silicon-on-insulator (SOI) on chip optical arbitrary waveform generator, which is based on Taylor synthesis method. In our scheme, a Gaussian pulse is launched to some cascaded microrings to obtain first-, second- and third-order differentiations. By controlling amplitude and phase of the initial pulse and successive differentiations, we can realize an arbitrary waveform generator according to Taylor expansion. We obtain several typical waveforms such as square waveform, triangular waveform, flat-top waveform, sawtooth waveform, Gaussian waveform and so on. Unlike other schemes based on Fourier synthesis or frequency-to-time mapping, our scheme is based on Taylor synthesis method. Our scheme does not require any spectral disperser or large dispersion, which are difficult to fabricate on chip. Our scheme is compact and capable for integration with electronics.
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32
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Zou J, Yu Y, Zhang X. Two-dimensional grating coupler with a low polarization dependent loss of 0.25 dB covering the C-band. OPTICS LETTERS 2016; 41:4206-4209. [PMID: 27628358 DOI: 10.1364/ol.41.004206] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We design and demonstrate a two-dimensional grating coupler (2D GC) with a low polarization dependent loss (PDL) based on the silicon-on-insulator (SOI) platform. Using a grating cell consisting of five cylinders and carefully optimizing the distances between the cylinders, a maximum PDL of 0.25 dB covering the C-band is realized, which is 1.25 dB better than a conventional 2D GC with a single cylinder etching pattern fabricated on the same SOI wafer.
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33
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Qiu H, Jiang J, Yu P, Dai T, Yang J, Yu H, Jiang X. Silicon band-rejection and band-pass filter based on asymmetric Bragg sidewall gratings in a multimode waveguide. OPTICS LETTERS 2016; 41:2450-2453. [PMID: 27244386 DOI: 10.1364/ol.41.002450] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
A silicon photonic wire filter based on an asymmetric sidewall Bragg grating in a multimode silicon-on-insulator strip waveguide is demonstrated. The operating principle is based on the contra-directional coupling between the transverse electric fundamental (TE0) and first-order (TE1) modes, which is enabled by the asymmetric spatially periodic refractive-index perturbations. An asymmetric Y-junction is cascaded at the input port of the filter so as to drop the Bragg reflection. Compared with conventional Bragg grating-based filters, this device eliminates the back reflection at the input port and the 6 dB inherent insertion loss at the drop port; moreover, a narrow 3 dB bandwidth can be obtained with a large critical dimension as a result of the weak coupling strength between the TE0 and TE1 modes inside the multimode waveguide. Experimental results show that a bandwidth of ∼2.8 nm is achieved by a large corrugation width of 150 nm. The insertion loss at the drop port is -2.1 dB, and the extinction ratio is -33 dB at the through port.
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34
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Qi F, Ma Q, Wang Y, Zheng W. Large-aperture subwavelength grating couplers. APPLIED OPTICS 2016; 55:2960-2966. [PMID: 27139860 DOI: 10.1364/ao.55.002960] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Subwavelength nanostructure grating couplers fabricated on silicon-on-insulator substrates are used to simplify the fabrication process while maintaining high coupling efficiency. The main obstacle for their application in photonic integrated circuits is the small aperture size of the nanostructure when TE polarization is involved, since they are difficult to achieve with 193 nm deep-ultraviolet lithography and cause problems in inductively coupled plasma etching. A larger lateral period has been used to increase the aperture size. Here, we propose that decreasing the effective index of the nanostructure can also enlarge the aperture size. We analyze the two methods in detail with a rectangle-hole nanostructure and 220 nm thick waveguide layer, aiming at TE polarization centered at 1560 nm. We find performance degenerations for large lateral periods, and this can be simply compensated by adjusting the width of the rectangle hole. The minimum linewidth of the nanostructure can reach 240 nm, while the coupling efficiency is just slightly decreased. The backreflections of a large-aperture grating increase but stay in the same order with ordinary ones, and we also show that this can be overcome by apodizing the grating structure. Finally, we experimentally demonstrate the designed large-aperture grating couplers and the coupling efficiencies are higher than 35%, and reach a rectangle-hole width.
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35
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Zou J, Yu Y, Zhang X. Single step etched two dimensional grating coupler based on the SOI platform. OPTICS EXPRESS 2015; 23:32490-32495. [PMID: 26699038 DOI: 10.1364/oe.23.032490] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We design and demonstrate a single step etched two dimensional grating coupler (2D GC) based on the silicon-on-insulator (SOI) platform using subwavelength cylinders. Taking the lag effect into consideration, the 2D GC is manufactured in the same lithography and etching processes with the strip waveguide. The measured coupling loss of the proposed 2D GC is -6.0 dB, which is comparable with conventional shallowly etched 2D GC, realizing a fabrication simplification without performance degradation.
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36
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Huang TL, Zheng AL, Dong JJ, Gao DS, Zhang XL. Terahertz-bandwidth photonic temporal differentiator based on a silicon-on-isolator directional coupler. OPTICS LETTERS 2015; 40:5614-5617. [PMID: 26625064 DOI: 10.1364/ol.40.005614] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We experimentally demonstrate a terahertz-bandwidth photonic differentiator employing a silicon-on-insulator directional coupler. The integrated waveguide coupler with two identical paralleled strip waveguides achieves a first-order differentiator when full energy coupling is met from one waveguide to another. The integrated waveguide coupler can offer different operation bandwidths by changing the length and gap of the strip waveguides. Due to the large 3 dB bandwidth of the directional coupler, we implement the first differentiator with an operation bandwidth of 1.25 THz. The performance of this photonic differentiator is tested using Gaussian-like pulses with a pulsewidth of 2.8 ps, 4 ps, 6 ps, 8 ps, and 10 ps, respectively. The differentiation processing errors and relative energy efficiency are also discussed. This silicon chip may have potential applications in integrated photonic computing circuits with sub-picosecond pulses.
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37
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Wang J, Chen LR. Low crosstalk Bragg grating/Mach-Zehnder interferometer optical add-drop multiplexer in silicon photonics. OPTICS EXPRESS 2015; 23:26450-26459. [PMID: 26480158 DOI: 10.1364/oe.23.026450] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We characterize the interferometric crosstalk and system performance of two optical add-drop multiplexer (OADM) designs based on Bragg grating/Mach-Zehnder interferometers implemented in silicon-on-insulator. Both OADM designs exhibit low crosstalk and negligible crosstalk-induced power penalties over their 3 dB bandwidths. The devices are tolerant to wavelength drift and misalignment between the transmitter and OADM; moreover, their designs can be optimized further to enable high performance operation in WDM systems.
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38
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Tseng HL, Chen E, Rong H, Na N. High-performance silicon-on-insulator grating coupler with completely vertical emission. OPTICS EXPRESS 2015; 23:24433-24439. [PMID: 26406648 DOI: 10.1364/oe.23.024433] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We study the physical concept of utilizing a critical coupling to obtain a high-performance grating coupler with completely vertical emission on a silicon-on-insulator substrate. Following our design strategy, we numerically show that when our grating coupler is coupled to a standard single-mode fiber operating at 1310 nm wavelength, a -1.46 dB coupling loss, a 20 nm spectral full-width-half-maximum, and a -24 dB back reflection can be achieved at the same time without full optimization. A practical design that largely relaxes the stringent lithography requirement is also proposed and presented.
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39
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Cheben P, Schmid JH, Wang S, Xu DX, Vachon M, Janz S, Lapointe J, Painchaud Y, Picard MJ. Broadband polarization independent nanophotonic coupler for silicon waveguides with ultra-high efficiency. OPTICS EXPRESS 2015; 23:22553-22563. [PMID: 26368222 DOI: 10.1364/oe.23.022553] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Coupling of light to and from integrated optical circuits has been recognized as a major practical challenge since the early years of photonics. The coupling is particularly difficult for high index contrast waveguides such as silicon-on-insulator, since the cross-sectional area of silicon wire waveguides is more than two orders of magnitude smaller than that of a standard single-mode fiber. Here, we experimentally demonstrate unprecedented control over the light coupling between the optical fiber and silicon chip by constructing the nanophotonic coupler with ultra-high coupling efficiency simultaneously for both transverse electric and transverse magnetic polarizations. We specifically demonstrate a subwavelength refractive index engineered nanostructure to mitigate loss and wavelength resonances by suppressing diffraction effects, enabling a coupling efficiency over 92% (0.32 dB) and polarization independent operation for a broad spectral range exceeding 100 nm.
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40
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Guan X, Ding Y, Frandsen LH. Ultra-compact broadband higher order-mode pass filter fabricated in a silicon waveguide for multimode photonics. OPTICS LETTERS 2015; 40:3893-3896. [PMID: 26274687 DOI: 10.1364/ol.40.003893] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
An ultra-compact and broadband higher order-mode pass filter in a 1D photonic crystal silicon waveguide is proposed and experimentally demonstrated. The photonic crystal is designed for the lower order mode to work in the photonic band gap, while the higher order mode is located in the air band. Consequently, light on the lower order mode is prohibited to pass through the filter, while light on a higher order mode can be converted to a Bloch mode in the photonic crystal and pass through the filter with low insertion loss. As an example, we fabricate a ∼15-μm-long first-order-mode pass filter that filters out the fundamental mode and provides a measured insertion loss of ∼1.8 dB for the first-order-mode pass signals. The extinction ratio is measured to be around 50 dB (with a variation of ±10 dB due to the detection limitation of the measurement setup) in the measured wavelength range from 1480 to 1580 nm. Additionally, calculations predict the extinction ratio to be larger than 50 dB in a 170 nm broad bandwidth.
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41
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Ding Y, Zhu X, Xiao S, Hu H, Frandsen LH, Mortensen NA, Yvind K. Effective Electro-Optical Modulation with High Extinction Ratio by a Graphene-Silicon Microring Resonator. NANO LETTERS 2015; 15:4393-400. [PMID: 26042835 DOI: 10.1021/acs.nanolett.5b00630] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Graphene opens up for novel optoelectronic applications thanks to its high carrier mobility, ultralarge absorption bandwidth, and extremely fast material response. In particular, the opportunity to control optoelectronic properties through tuning of the Fermi level enables electro-optical modulation, optical-optical switching, and other optoelectronics applications. However, achieving a high modulation depth remains a challenge because of the modest graphene-light interaction in the graphene-silicon devices, typically, utilizing only a monolayer or few layers of graphene. Here, we comprehensively study the interaction between graphene and a microring resonator, and its influence on the optical modulation depth. We demonstrate graphene-silicon microring devices showing a high modulation depth of 12.5 dB with a relatively low bias voltage of 8.8 V. On-off electro-optical switching with an extinction ratio of 3.8 dB is successfully demonstrated by applying a square-waveform with a 4 V peak-to-peak voltage.
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Affiliation(s)
- Yunhong Ding
- †Department of Photonics Engineering and ‡Center for Nanostructured Graphene, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
| | - Xiaolong Zhu
- †Department of Photonics Engineering and ‡Center for Nanostructured Graphene, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
| | - Sanshui Xiao
- †Department of Photonics Engineering and ‡Center for Nanostructured Graphene, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
| | - Hao Hu
- †Department of Photonics Engineering and ‡Center for Nanostructured Graphene, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
| | - Lars Hagedorn Frandsen
- †Department of Photonics Engineering and ‡Center for Nanostructured Graphene, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
| | - N Asger Mortensen
- †Department of Photonics Engineering and ‡Center for Nanostructured Graphene, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
| | - Kresten Yvind
- †Department of Photonics Engineering and ‡Center for Nanostructured Graphene, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
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42
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Bozzola A, Carroll L, Gerace D, Cristiani I, Andreani LC. Optimising apodized grating couplers in a pure SOI platform to -0.5 dB coupling efficiency. OPTICS EXPRESS 2015; 23:16289-16304. [PMID: 26193602 DOI: 10.1364/oe.23.016289] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We present a theoretical optimisation of 1D apodized grating couplers in a "pure" Silicon-On-Insulator (SOI) architecture, i.e. without any bottom reflector element, by means of a general mutative method. We perform a comprehensive 2D Finite Difference Time Domain study of chirped and apodized grating couplers in 220 nm SOI, and demonstrate that the global maximum coupling efficiency in that platform is capped to 65% (-1.9 dB). Moving to designs with thicker Si-layers, we identify a new record design in 340 nm SOI, with a simulated coupling efficiency of 89% (-0.5 dB). Going to thicker Si layers does not further improve the efficiency, implying that -0.5 dB may be a global maximum for a grating coupler in SOI without a bottom-reflector. Even after allowing for 193 nm UV-lithographic fabrication constraints, the 340 nm design still offers -0.7 dB efficiency. These new apodized designs are the first pure SOI couplers compatible with deep-UV lithography to offer better than -1 dB insertion losses. With only very minor changes to existing deposition and lithography recipes, they are compatible with the multi-project wafer runs already offered by Si-Photonics foundries.
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43
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Liao S, Ding Y, Dong J, Yang T, Chen X, Gao D, Zhang X. Arbitrary waveform generator and differentiator employing an integrated optical pulse shaper. OPTICS EXPRESS 2015; 23:12161-12173. [PMID: 25969304 DOI: 10.1364/oe.23.012161] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We propose and demonstrate an optical arbitrary waveform generator and high-order photonic differentiator based on a four-tap finite impulse response (FIR) silicon-on-insulator (SOI) on-chip circuit. Based on amplitude and phase modulation of each tap controlled by thermal heaters, we obtain several typical waveforms such as triangular waveform, sawtooth waveform, square waveform and Gaussian waveform, etc., assisted by an optical frequency comb injection. Unlike other proposed schemes, our scheme does not require a spectral disperser which is difficult to fabricate on chip with high resolution. In addition, we demonstrate first-, second- and third-order differentiators based on the optical pulse shaper. Our scheme can switch the differentiator patterns from first- to third-order freely. In addition, our scheme has distinct advantages of compactness, capability for integration with electronics.
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44
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Gui C, Li C, Yang Q, Wang J. Demonstration of terabit-scale data transmission in silicon vertical slot waveguides. OPTICS EXPRESS 2015; 23:9736-9745. [PMID: 25969012 DOI: 10.1364/oe.23.009736] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We design and fabricate silicon vertical slot waveguides for terabit-scale data transmission. The designed silicon photonic device is composed of apodized grating couplers, strip waveguides, strip-to-slot/slot-to-strip mode converters, and slot waveguide. Tight light confinement in the nano-scale air slot region is achieved in the silicon vertical slot waveguide which features relatively lower nonlinearity compared to silicon strip waveguide. Using the fabricated silicon photonic devices, we first demonstrate ultra-wide bandwidth 1.8-Tbit/s data transmission through a 2-mm-long silicon vertical slot waveguide using 161 wavelength-division multiplexing (WDM) channels each carrying 11.2-Gbit/s orthogonal frequency-division multiplexing (OFDM) 16-ary quadrature amplitude modulation (16-QAM) signal. All 161 WDM channels achieve bit-error rate (BER) less than 1e-3 after on-chip data transmission. We further demonstrate terabit-scale data transmission through four silicon vertical slot waveguides with different lengths (1 mm, 2 mm, 3.1 mm, 12.2 mm). The optical signal-to-noise ratio (OSNR) penalties of data transmission through four silicon vertical slot waveguides are 1, 2, 3.2 and 4.5 dB at a BER of 1e-3, respectively. The obtained results indicate that the presented silicon vertical slot waveguide might be an alternative promising candidate facilitating chip-scale high-speed optical interconnections.
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Subbaraman H, Xu X, Hosseini A, Zhang X, Zhang Y, Kwong D, Chen RT. Recent advances in silicon-based passive and active optical interconnects. OPTICS EXPRESS 2015; 23:2487-2510. [PMID: 25836116 DOI: 10.1364/oe.23.002487] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Silicon photonics has experienced phenomenal transformations over the last decade. In this paper, we present some of the notable advances in silicon-based passive and active optical interconnect components, and highlight some of our key contributions. Light is also cast on few other parallel technologies that are working in tandem with silicon-based structures, and providing unique functions not achievable with any single system acting alone. With an increasing utilization of CMOS foundries for silicon photonics fabrication, a viable path for realizing extremely low-cost integrated optoelectronics has been paved. These advances are expected to benefit several application domains in the years to come, including communication networks, sensing, and nonlinear systems.
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Ding Y, Ye F, Peucheret C, Ou H, Miyamoto Y, Morioka T. On-chip grating coupler array on the SOI platform for fan-in/fan-out of MCFs with low insertion loss and crosstalk. OPTICS EXPRESS 2015; 23:3292-3298. [PMID: 25836187 DOI: 10.1364/oe.23.003292] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We report the design and fabrication of a compact multi-core fiber fan-in/fan-out using a grating coupler array on the SOI platform. The grating couplers are fully-etched, enabling the whole circuit to be fabricated in a single lithography and etching step. Thanks to the apodized design for the grating couplers and the introduction of an aluminum reflective mirror, a highest coupling efficiency of -3.8 dB with 3 dB coupling bandwidth of 48 nm and 1.5 dB bandwidth covering the whole C band, together with crosstalk lower than -32 dB are demonstrated.
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Liao S, Ding Y, Peucheret C, Yang T, Dong J, Zhang X. Integrated programmable photonic filter on the silicon-on-insulator platform. OPTICS EXPRESS 2014; 22:31993-31998. [PMID: 25607167 DOI: 10.1364/oe.22.031993] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We propose and demonstrate a silicon-on-insulator (SOI) on-chip programmable filter based on a four-tap finite impulse response structure. The photonic filter is programmable thanks to amplitude and phase modulation of each tap controlled by thermal heaters. We further demonstrate the tunability of the filter central wavelength, bandwidth and variable passband shape. The tuning range of the central wavelength is at least 42% of the free spectral range. The bandwidth tuning range is at least half of the free spectral range. Our scheme has distinct advantages of compactness, capability for integrating with electronics.
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Zou J, Yu Y, Ye M, Liu L, Deng S, Xu X, Zhang X. Short and efficient mode-size converter designed by segmented-stepwise method. OPTICS LETTERS 2014; 39:6273-6276. [PMID: 25361332 DOI: 10.1364/ol.39.006273] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We present an efficient segmented-stepwise method to design a short and low-loss mode-size converter. A silicon-on-insulator platform-based converter with 20 μm length and 95.2% conversion efficiency is acquired by taking only 10 optimization generations using 2D-FDTD method. A 3D-FDTD simulation is performed to verify the calculated results, returning an efficiency of 92.1%. The proposed device can be used to connect a 12-μm-wide waveguide and a 0.5-μm-wide single-mode waveguide, with comparable performance of a regular scheme using 150-μm-long linear taper. For demonstration, the converter was fabricated by electron-beam-lithography and inductively-coupled-plasma etching. A conversion loss of -0.62±0.02 dB at 1550 nm was experimentally measured.
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Ding Y, Peucheret C, Ou H, Yvind K. Fully etched apodized grating coupler on the SOI platform with -0.58 dB coupling efficiency. OPTICS LETTERS 2014; 39:5348-50. [PMID: 26466268 DOI: 10.1364/ol.39.005348] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
We design and fabricate an ultrahigh coupling efficiency (CE) fully etched apodized grating coupler on the silicon-on-insulator (SOI) platform using subwavelength photonic crystals and bonded aluminum mirror. Fabrication error sensitivity and coupling angle dependence are experimentally investigated. A record ultrahigh CE of -0.58 dB with a 3 dB bandwidth of 71 nm and low back reflection are demonstrated.
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Vukovic D, Ding Y, Hu H, Ou H, Oxenløwe LK, Peucheret C. Polarization-insensitive wavelength conversion of 40 Gb/s NRZ-DPSK signals in a silicon polarization diversity circuit. OPTICS EXPRESS 2014; 22:12467-12474. [PMID: 24921364 DOI: 10.1364/oe.22.012467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Polarization insensitive wavelength conversion of a 40 Gb/s non-return-to-zero (NRZ) differential phase-shift keying (DPSK) data signal is demonstrated using four-wave mixing (FWM) in a silicon nanowire circuit. Polarization independence is achieved using a diversity circuit based on polarization rotators and splitters, which is fabricated by a simple process on the silicon-on-insulator (SOI) platform. Error-free performance is achieved with only 0.5 dB of power penalty compared to the wavelength conversion of a signal with well optimized input polarization. Additionally, data transmission over 161 km standard single-mode fiber (SSMF) is demonstrated at 40 Gb/s using optical phase conjugation (OPC) in the proposed circuit.
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