An improved curved grating demultiplexer based on silicon-on-insulator platform

Abstract

This article proposes two basic principles to address the astigmatism problem of traditional Rowland gratings. Ray tracing method is employed to analyze the correlation between the optical performance of gratings and the structural parameters, and further, optimize the grating structure. Using the proposed principles, we design a 1×4 demultiplexer with an ultracompact footprint of 97 × 73 μm2, which is suitable of the coarse wavelength division multiplexing (CWDM) system, where the wavelength spacing is 10 nm. The numerical calculation results show that the channel crosstalk between the four channels of the device is less than −40 dB, the insertion loss is between −1.35 dB and −1.80 dB, and the channel uniformity is better than 0.45 dB. The structure proposed curved grating in this article offers broad applications in high-density integrated photonic circuits.