Author Affiliations
Abstract
1 Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China
2 e-mail: hailongzhou@hust.edu.cn
Optical computing has shown immense application prospects in the post-Moore era. However, as a crucial component of logic computing, the digital multiplier can only be realized on a small scale in optics, restrained by the limited functionalities and inevitable loss of optical nonlinearity. In this paper, we propose a time-space multiplexed architecture to realize large-scale photonic-electronic digital multiplication. We experimentally demonstrate an -bit photonic-electronic digital multiplier, and the multiplication with a 32-bit number is further executed at 25 Mbit/s to demonstrate its extensibility and functionality. Moreover, the proposed architecture has the potential for on-chip implementation, and a feasible integration scheme is provided. We believe the time-space multiplexed photonic-electronic digital multiplier will open up a promising avenue for large-scale photonic digital computing.
Photonics Research
2024, 12(3): 499
Author Affiliations
Abstract
1 Wuhan National Laboratory for Optoelectronics & School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China
2 School of Mechanical Engineering and Electronic Information, China University of Geosciences, Wuhan 430074, China
3 Optics Valley Laboratory, Wuhan 430074, China
4 Xidian University, Xi’an 710126, China
5 e-mail: yuyu@mail.hust.edu.cn
6 e-mail: xlzhang@mail.hust.edu.cn
High-performance germanium photodiodes are crucial components in silicon photonic integrated circuits for large-capacity data communication. However, the bandwidths of most germanium photodiodes are limited by the intractable resistance–capacitance parasitic effect. Here, we introduce a unique U-shaped electrode to alleviate this issue, reducing the parasitic effect by 36% without compromising any other performance. Experimentally, a large bandwidth of 103 GHz, an optical responsivity of 0.95 A/W at 1550 nm, and a dark current as low as 1.3 nA are achieved, leading to a record high specific detectivity. This is the first breakthrough to 100 GHz bandwidth among all vertical germanium photodiodes, to the best of our knowledge. Open eye diagrams of 120 Gb/s on-off keying and 200 Gb/s four-level pulse amplitude signals are well received. This work provides a promising solution for chip-based ultra-fast photodetection.
Photonics Research
2024, 12(1): 1
Author Affiliations
Abstract
1 Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China
2 The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen, 518057, China
3 Photonics Research Institute, Department of Electrical Engineering, The Hong Kong Polytechnic University, Hong Kong 999077, China
4 Department of Physics, Hong Kong Baptist University, Kowloon Tong, 999077 Hong Kong, China
The increasing amount of data exchange requires higher-capacity optical communication links. Mode division multiplexing (MDM) is considered as a promising technology to support the higher data throughput. In an MDM system, the mode generator and sorter are the backbone. However, most of the current schemes lack the programmability and universality, which makes the MDM link susceptible to the mode crosstalk and environmental disturbances. In this paper, we propose an intelligent multimode optical communication link using universal mode processing (generation and sorting) chips. The mode processor consists of a programmable 4 × 4 Mach Zehnder interferometer (MZI) network and can be intelligently configured to generate or sort both quasi linearly polarized (LP) modes and orbital angular momentum (OAM) modes in any desired routing state. We experimentally establish a chip-to-chip MDM communication system. The mode basis can be freely switched between four LP modes and four OAM modes. We also demonstrate the multimode optical communication capability at a data rate of 25 Gbit/s. The proposed scheme shows significant advantages in terms of universality, intelligence, programmability and resistance to mode crosstalk, environmental disturbances, and fabrication errors, demonstrating that the MZI-based reconfigurable mode processor chip has great potential in long-distance chip-to-chip multimode optical communication systems.
Author Affiliations
Abstract
1 Huazhong University of Science and Technology, School of Optical and Electronic Information, Wuhan National Laboratory for Optoelectronics, Wuhan, China
2 Optics Valley Laboratory, Wuhan, China
Silicon nitride (Si3N4) waveguides with high confinement and low loss have been widely used in integrated nonlinear photonics. Indeed, state-of-the-art ultralow-loss Si3N4 waveguides are all fabricated using complex fabrication processes, and all of those reported that high Q microring resonators (MRRs) are fabricated in laboratories. We propose and demonstrate an ultralow-loss Si3N4 racetrack MRR by shaping the mode using a uniform multimode structure to reduce its overlap with the waveguide. The MRR is fabricated by the standard multi project wafer (MPW) foundry process. It consists of two multimode straight waveguides (MSWs) connected by two multimode waveguide bends (MWBs). In particular, the MWBs are based on modified Euler bends, and an MSW directional coupler is used to avoid higher-order mode excitation. In this way, although a multimode waveguide is used in the MRR, only the fundamental mode is excited and transmitted with ultralow loss. Meanwhile, thanks to the 180 deg Euler bend, a compact chip footprint of 2.226 mm perimeter with an effective radius as small as 195 μm and a waveguide width of 3 μm is achieved. Results show that based on the widely used MPW process, a propagation loss of only 3.3 dB / m and a mean intrinsic Q of around 10.8 million are achieved for the first time.
silicon nitride microring resonator ultrahigh-Q factor Advanced Photonics Nexus
2023, 2(4): 046007
Author Affiliations
Abstract
1 Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China
2 Optics Valley Laboratory, Wuhan 430074, China
3 Galileo Advanced Technology Lab, Huawei Technologies, Shenzhen 518129, China
4 Institute of Strategic Research, Huawei Technologies, Shenzhen 518129, China
5 e-mail: xuwenwei@huawei.com
6 e-mail: jjdong@mail.hust.edu.cn
corresponding author guidelines for details."?>As a resonator-based optical hardware in analog optical computing, a microring synapse can be straightforwardly configured to simulate the connection weights between neurons, but it faces challenges in precision and stability due to cross talk and environmental perturbations. Here, we propose and demonstrate a self-calibration scheme with dual-wavelength synchronization to monitor and calibrate the synaptic weights without interrupting the computation tasks. We design and fabricate an integrated microring synapse and deploy our self-calibration scheme to validate its effectiveness. The precision and robustness are evaluated in the experiments with favorable performance, achieving 2-bit precision improvement and excellent robustness to environmental temperature fluctuations (the weights can be corrected within 1 s after temperature changes 0.5°C). Moreover, we demonstrate matrix inversion tasks based on Newton iterations beyond 7-bit precision using this microring synapse. Our scheme provides an accurate and real-time weight calibration independently parallel from computations and opens up new perspectives for precision boost solutions to large-scale analog optical computing.
Photonics Research
2023, 11(2): 347
Author Affiliations
Abstract
1 Huazhong University of Science and Technology, Wuhan National Laboratory for Optoelectronics and School of Optical and Electronic Information, Wuhan, China
2 China Information and Communication Technologies Group Corporation, State Key Laboratory of Optical Communication Technologies and Networks, Wuhan, China
3 National Information Optoelectronics Innovation Center, Wuhan, China
4 Optics Valley Laboratory, Wuhan, China
Parity‐time (PT) symmetry breaking offers mode selection capability for facilitating single‐mode oscillation in the optoelectronic oscillator (OEO) loop. However, most OEO implementations depend on discrete devices, which impedes proliferation due to size, weight, power consumption, and cost. In this work, we propose and experimentally demonstrate an on-chip tunable PT‐symmetric OEO. A tunable microwave photonic filter, a PT‐symmetric mode‐selective architecture, and two photodetectors are integrated on a silicon‐on‐insulator chip. By exploiting an on‐chip Mach–Zehnder interferometer to match the gain and loss of two mutually coupled optoelectronic loops, single‐mode oscillation can be obtained. In the experiment, the oscillation frequency of the on-chip tunable PT‐symmetric OEO can be tuned from 0 to 20 GHz. To emulate the integrated case, the OEO loop length is minimized, and no extra-long fiber is used in the experiment. When the oscillation frequency is 13.67 GHz, the single‐sideband phase noise at 10-kHz offset frequency is -80.96 dBc / Hz and the side mode suppression ratio is 46 dB. The proposed on-chip tunable PT‐symmetric OEO significantly reduces the footprint of the system and enhances mode selection.
silicon photonics optoelectronic oscillator parity-time symmetry Advanced Photonics Nexus
2023, 2(1): 016004
1 华中科技大学光学与电子信息学院武汉光电国家研究中心，湖北 武汉 430074
2 湖北光谷实验室，湖北 武汉 430074
光电子轨道断层成像是有机纳米材料研究中一种实验和理论相结合的技术，其核心是建立光电子角分布能谱和分子初始态轨道结构之间的直接联系。研究者通过较为简易的平面波近似，可以实现对表面共轭分子价带轨道角分辨光电子能谱的精确分析，从而研究它们的电学、光学和化学特性。介绍了光电子轨道断层成像技术的理论基础和实验手段，综述了近年来该技术在确定分子的几何结构、测量界面电学相互作用、获得时间分辨轨道图像等领域的诸多应用，并介绍了该技术结合超快激光等相关实验技术的最新进展。
光谱学 有机纳米材料 光电子能谱 固体‑分子界面 分子轨道 断层成像 超快泵浦‑探测光谱
Author Affiliations
Abstract
1 Huazhong University of Science and Technology, Wuhan National Laboratory for Optoelectronics, Wuhan, China
2 Nanyang Technological University, School of Electrical and Electronic Engineering, Singapore
3 Optics Valley Laboratory, Wuhan, China
Microlaser with multiple lasing bands is critical in various applications, such as full-color display, optical communications, and computing. Here, we propose a simple and efficient method for homogeneously doping rare earth elements into a silica whispering-gallery microcavity. By this method, an Er-Yb co-doped silica microsphere cavity with the highest quality (Q) factor (exceeding 108) among the rare-earth-doped microcavities is fabricated to demonstrate simultaneous and stable lasing covering ultraviolet, visible, and near-infrared bands under room temperature and a continuous-wave pump. The thresholds of all the lasing bands are estimated to be at the submilliwatt level, where both the ultraviolet and violet continuous wave upconversion lasing from rare earth elements has not been separately demonstrated under room temperature until this work. This ultrahigh-Q doped microcavity is an excellent platform for high-performance multiband microlasers, ultrahigh-precision sensors, optical memories, and cavity-enhanced light–matter interaction studies.
multiband microlasers whispering-gallery microcavities rare earth elements upconversion Advanced Photonics
2022, 4(4): 046003
