采用硅基二氧化硅材料，针对G.698.4标准，设计并制作了适用于5G前传的20通道循环型阵列波导光栅，通道间隔为100 GHz。相较于传统的周期性阵列波导光栅结构，采用的2×20 循环型阵列波导光栅结构可实现通道波长的严格对准，且插损均匀性更高。另外，采用指数型锥形波导取代矩形多模干涉结构以实现阵列波导光栅通带平坦化，减小因波导结构上的突变带来的损耗，且不带来光谱性能的恶化。通过机械补偿无热封装后，制备的20通道循环型阵列波导光栅模块损耗约为5.5 dB，在-40 ℃/25 ℃/80 ℃三温温度变化时，波长偏移量在-40 ~80 pm范围内。该无热模块具有小型化、低成本、大规模化生产的优势，可广泛应于5G前传网络。

针对数据中心互连用波分复用芯片需求，采用折射率差为1.5%的硅基二氧化硅光波导，设计并制备了应用于数据中心发射端的同侧、小型化、低损耗4通道粗波分复用芯片，尺寸为6.6 mm×2.2 mm，最小插入损耗小于2.33 dB，1 dB带宽大于11.35 nm，偏振相关损耗小于0.14 dB，波长精准度偏差小于0.38 nm。完全满足数据中心光互连波分复用芯片商用指标要求。

Quantum key distribution (QKD) provides a solution for communication of unconditional security. However, the quantum channel disturbance in the field severely increases the quantum bit-error rate, degrading the performance of a QKD system. Here we present a setup comprising silica planar light wave circuits (PLCs), which is robust against the channel polarization disturbance. Our PLCs are based on the asymmetric Mach–Zehnder interferometer (AMZI), integrated with a tunable power splitter and thermo-optic phase modulators. The polarization characteristics of the AMZI PLC are investigated by a novel pulse self-interfering method to determine the operation temperature of implementing polarization insensitivity. Over a 20 km fiber channel with 30 Hz polarization scrambling, our time-bin phase-encoding QKD setup is characterized with an interference fringe visibility of 98.72%. The extinction ratio for the phase states is kept between 18 and 21 dB for 6 h without active phase correction.

A high-performance monolithic integrated wavelength division multiplexing silicon (Si) photonics receiver chip is fabricated on a silicon-on-insulator platform. The receiver chip has a 25-channel Si nanowire-arrayed waveguide grating, and each channel is integrated with a high-speed waveguide Ge-on-Si photodetector. The central wavelength, optical insertion loss, and cross talk of the array waveguide grating are 1550.6?nm, 5–8?dB, and ?12–?15??dB, respectively. The photodetectors show low dark current density of 16.9??mA/cm2 at ?1??V and a high responsivity of 0.82?A/W at 1550?nm. High bandwidths of 23 and 29?GHz are achieved at 0 and ?1??V, respectively. Each channel can operate at 50?Gbps with low input optical power even under zero bias, which realizes an aggregate data rate of 1.25?Tbps.

Both the 4×20 GHz coarse wavelength division multiplexing and LAN-WDM receiver optical sub-assemblies (ROSAs) were developed. The ROSA package was hybrid integrated with a planar lightwave circuit arrayed waveguide grating (AWG) with 2% refractive index difference and a four-channel top-illuminated positive-intrinsic-negative photodetector (PD) array. The output waveguides of the AWG were designed in a multimode structure to provide flat-top optical spectra, and their end facet was angle-polished to form a total internal reflection interface to realize vertical coupling with a PD array. The maximum responsivity of ROSA was about 0.4 A/W, and its 3 dB bandwidth of frequency response was up to 20 GHz for each transmission lane. The hybrid integrated ROSA would be a cost-effective and easy-assembling solution for 100 GbE data center interconnections.