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.

Emerging wearable devices would benefit from integrating ductile photovoltaic light-harvesting power sources. In this work, we report a small-molecule acceptor (SMA), also known as a non–fullerene acceptor (NFA), designed for stretchable organic solar cell ( s -OSC) blends with large mechanical compliance and performance. Blends of the organosilane-functionalized SMA BTP-Si4 with the polymer donor PNTB6-Cl achieved a power conversion efficiency (PCE) of >16% and ultimate strain (ε _u ) of >95%. Typical SMAs suppress OSC blend ductility, but the addition of BTP-Si4 enhances it. Although BTP-Si4 is less crystalline than other SMAs, it retains considerable electron mobility and is highly miscible with PNTB6-Cl and is essential for enhancing ε _u . Thus, s -OSCs with PCE > 14% and operating normally under various deformations (>80% PCE retention under an 80% strain) were demonstrated. Analysis of several SMA-polymer blends revealed general molecular structure–miscibility–stretchability relationships for designing ductile blends.

Microwave photonic filter (MPF) is one of the key fundamental subsystems in microwave photonics, and it shows great potentiality in numbers of applications such as optoelectronic oscillator, microwave frequency measurement, and so forth. A narrowband bandpass MPF is highly desirable with its high selectivity in microwave photonic applications. However, a resonator with a high quality factor (>10 ⁶ ) is very difficult to fabricate on the mature silicon photonics platform without optimization, thus restraining the applications of the MPF. In this paper, we propose and experimentally demonstrate a tunable sub-gigahertz bandwidth MPF based on an ultrahigh quality factor silicon microring resonator. Most performance aspects of the MPF are well-balanced. A full width at half-maximum bandwidth of 170 MHz is achieved thanks to the ultrahigh total quality factor as 1.14 × 10 ⁶ of the microring resonator, and the average waveguide loss and the intrinsic Q factor of the microring resonator are calculated as 0.25 dB/cm and 2.67 × 10 ⁶ , respectively. The corresponding rejection ratio of the bandpass filter is 26.5 dB. Besides, the central frequency of the filter could be continuously tuned from 2.0 to 18.4 GHz with a microheater fabricated upon the microring, and a 16.4 GHz tuning range is achieved with the maximum power consumption of 14.4 mW. The device area is ~0.05 mm ² .

We propose large bandwidth and high fabrication-tolerance mode-order converters on the silicon-on-insulator platform based on novel compact tapers structures. Each of the converters is in a single waveguide. Designs of different symmetries with and without breaking the parities between odd and even modes are illustrated. The fabrication tolerances of the devices are also investigated. The simulation results show that high conversion efficiencies can be readily achieved over a wavelength range from 1520 nm to 1580 nm for all of the proposed devices. The average conversion efficiencies of TE1-to-TE0, TE2-to-TE0, TE3-to-TE0, TE2-to-TE1, TE3-to-TE1, and TE3-to-TE2 converters are −0.061 dB, −0.052 dB, −0.11 dB, −0.119 dB, −0.168 dB, and −0.154 dB, respectively. The conversion efficiencies have negligible degradations under normal width and thickness deviations.

Silicon photonics is promising for artificial neural networks computing owing to its superior interconnect bandwidth, low energy consumption and scalable fabrication. However, the lack of silicon-integrated and monitorable optical neurons limits its revolution in large-scale artificial neural networks. Here, we highlight nonlinear germanium-silicon photodiodes to construct on-chip optical neurons and a self-monitored all-optical neural network. With specifically engineered optical-to-optical and optical-to-electrical responses, the proposed neuron merges the all-optical activation and non-intrusive monitoring functions in a compact footprint of 4.3 × 8 μm². Experimentally, a scalable three-layer photonic neural network enables in situ training and learning in object classification and semantic segmentation tasks. The performance of this neuron implemented in a deep-scale neural network is further confirmed via handwriting recognition, achieving a high accuracy of 97.3%. We believe this work will enable future large-scale photonic intelligent processors with more functionalities but simplified architecture.

We propose and experimentally demonstrate an on-chip switchable mode exchange utilizing a Mach–Zehnder interferometer assisted by a phase shifter. The switchable functionality, which is essential for an advanced and reconfigurable optical network, can be realized by controlling the induced phase difference. The measured extinction ratio is $\sim 24\mathrm{dB}$ over the $C$ band for OFF–ON switchover. For demonstration, open and clear-eye diagrams can be observed when processing non-return-to-zero on–off keying signals at 10 Gb/s. The bit error rate measurements indicate a reasonable power penalty of less than 1 dB for two-mode exchange. The proposed device can further promote advanced and flexible mode-multiplexing optical networks.