Matrix computation, as a fundamental building block of information processing in science and technology, contributes most of the computational overheads in modern signal processing and artificial intelligence algorithms. Photonic accelerators are designed to accelerate specific categories of computing in the optical domain, especially matrix multiplication, to address the growing demand for computing resources and capacity. Photonic matrix multiplication has much potential to expand the domain of telecommunication, and artificial intelligence benefiting from its superior performance. Recent research in photonic matrix multiplication has flourished and may provide opportunities to develop applications that are unachievable at present by conventional electronic processors. In this review, we first introduce the methods of photonic matrix multiplication, mainly including the plane light conversion method, Mach-Zehnder interferometer method and wavelength division multiplexing method. We also summarize the developmental milestones of photonic matrix multiplication and the related applications. Then, we review their detailed advances in applications to optical signal processing and artificial neural networks in recent years. Finally, we comment on the challenges and perspectives of photonic matrix multiplication and photonic acceleration. 

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Photonic matrix multiplication lights up photonic accelerator and beyond

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Graphene-based photodetectors have attracted significant attention for high-speed optical communication due to their large bandwidth, compact footprint, and compatibility with silicon-based photonics platform. Large-bandwidth silicon-based optical coherent receivers are crucial elements for large-capacity optical communication networks with advanced modulation formats. Here, we propose and experimentally demonstrate an integrated optical coherent receiver based on a 90-degree optical hybrid and graphene-on-plasmonic slot waveguide photodetectors, featuring a compact footprint and a large bandwidth far exceeding 67 GHz. Combined with the balanced detection, 90 Gbit/s binary phase-shift keying signal is received with a promoted signal-to-noise ratio. Moreover, receptions of 200 Gbit/s quadrature phase-shift keying and 240 Gbit/s 16 quadrature amplitude modulation signals on a single-polarization carrier are realized with a low additional power consumption below 14 fJ/bit. This graphene-based optical coherent receiver will promise potential applications in 400-Gigabit Ethernet and 800-Gigabit Ethernet technology, paving another route for future high-speed coherent optical communication networks. Graphene-based photodetectors have many advantages for applications. Here, the authors demonstrate a high-speed optical coherent receiver for optical communications based on graphene-on-plasmonic slot waveguide photodetectors.

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Ultrahigh-speed graphene-based optical coherent receiver.

Biocompatible and Biodegradable Polymer Optical Fiber for Biomedical Application: A Review

In recent years, optical modulators, photodetectors, (de)multiplexers, and heterogeneously integrated lasers based on silicon optical platforms have been verified. The performance of some devices even surpasses the traditional III-V and photonic integrated circuit (PIC) platforms, laying the foundation for large-scale photonic integration. Silicon photonic technology can overcome the limitations of traditional transceiver technology in high-speed transmission networks to support faster interconnection between data centers. In this article, we will review recent progress for silicon PICs. The first part gives an overview of recent achievements in silicon PICs. The second part introduces the silicon photonic building blocks, including low-loss waveguides, passive devices, modulators, photodetectors, heterogeneously integrated lasers, and so on. In the third part, the recent progress on high-capacity silicon photonic transceivers is discussed. In the fourth part, we give a review of high-capacity silicon photonic networks on chip. 

Silicon Photonics for High-Capacity Data Communications

Ultra-Compact High-Speed Polarization Division Multiplexing Optical Receiving Chip Enabled by Graphene-on-Plasmonic Slot Waveguide Photodetectors

Photo-mixing with its advantages of ultra-large bandwidth and precise tunability has emerged as an important technique for terahertz (THz) wave generation. Recently, graphene photodetectors exhibiting a large bandwidth are expected to further boost the development of integrated THz emitters. Here, we fabricate a sub-THz emitter based on a large-bandwidth silicon–plasmonic graphene (SPG) photodetector integrated with a broadband rounded bow-tie THz antenna. The SPG sub-THz emitter is experimentally demonstrated to emit sub-THz waves with a radiation spectrum from 50 to 300 GHz. A maximum sub-THz emission power of 5.4 nW is obtained at 145 GHz with only 3 mW input light power. The SPG sub-THz emitter can be fabricated by a CMOS-compatible process, which offers enormous opportunities for its use in a variety of THz applications.

Antenna-integrated silicon–plasmonic graphene sub-terahertz emitter

High-power silicon-based photodiodes are key components in many silicon photonics systems, such as microwave photonics systems, an optical interconnection system with multi-level modulation formats, etc. Usually, the saturation power of the silicon-germanium (Si-Ge) photodiode is limited by the space-charge screening (SCS) effect and the feasibility of the fabrication process. Here, we propose a high saturation power Si-Ge photodiode assisted by doping regulation. Through alleviating the SCS effect of the photodiode, we successfully demonstrate an 85.7% improvement on the saturation power and a 57% improvement on the -1 dB compression photocurrent. The proposed high-power Si-Ge photodiode requires no specific fabrication process and will promote the low-cost integrated silicon photonics systems for more applications.

High-power Si-Ge photodiode assisted by doping regulation

We report a waveguide Si-Ge avalanche photodiode using zero-change foundry processing. A 182 GHz gain-bandwidth product with a responsivity of 11.2 A/W at 1550 nm is experimentally demonstrated through hole-generated impact ionization.

Zhibin Jiang

Papers

Ultrahigh-speed graphene-based optical coherent receiver.

Ultra-Compact High-Speed Polarization Division Multiplexing Optical Receiving Chip Enabled by Graphene-on-Plasmonic Slot Waveguide Photodetectors

Antenna-integrated silicon–plasmonic graphene sub-terahertz emitter

High-power Si-Ge photodiode assisted by doping regulation

Waveguide Si-Ge Avalanche Photodiode Based on Hole-Generated Impact Ionization