Integrated spatial light receivers based on inverse design.

Abstract

Photonic integrated spatial light receivers play a crucial role in free space optical (FSO) communication systems. In this paper, we propose a 4-channel and 6-channel spatial light receiver based on a silicon-on-insulator (SOI) using an inverse design method, respectively. The 4-channel receiver has a square receiving area of 4.4 µm × 4.4 µm, which enables receiving four Hermite-Gaussian modes (HG00, HG01, HG10, and HG02) and converting them into fundamental transverse electric (TE00) modes with insertion losses (ILs) within 1.6∼2.1 dB and mean cross talks (MCTs) less than -16 dB, at a wavelength of 1550 nm. The 3 dB bandwidths of the four HG modes range from 28 nm to 46 nm. Moreover, we explore the impact of fabrication errors, including under/over etching and oxide thickness errors, on the performance of the designed device. Simulation results show that the 4-channel receiver is robust against fabrication errors. The designed 6-channel receiver, featuring a regular hexagon receiving area, is capable of receiving six modes (HG00, HG01, HG10, HG02, HG20, and HG11) with ILs within 2.3∼4.1 dB and MCTs less than -15 dB, at a wavelength of 1550 nm. Additionally, the receiver offers a minimum optical bandwidth of 26 nm.