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.

Microring lasers feature ultralow thresholds and inherent wavelength-division multiplexing functionalities, offering an attractive approach to miniaturizing photonics in a compact area. Here, we present static and dynamic properties of microring quantum dot lasers grown directly on exact (001) GaP/Si. Effectively, a single-mode operation was observed at 1.3 μm with modes at spectrally distant locations. High temperature stability with T0～103 K has been achieved with a low threshold of 3 mA for microrings with an outer ring radius of 15 μm and a ring waveguide width of 4 μm. Small signal modulation responses were measured for the first time for the microrings directly grown on silicon, and a 3 dB bandwidth of 6.5 GHz was achieved for a larger ring with an outer ring radius of 50 μm and a ring waveguide width of 4 μm. The directly modulated microring laser, monolithically integrated on a silicon substrate, can incur minimal real estate cost while offering full photonic functionality.