Inverse design of subwavelength gratings-assisted ultracompact 1.55/2 μm wavelength diplexer based on a bullet-shaped structure
摘要
As an effective and feasible method, inverse design has been widely used in the design of silicon-based photonic devices. We propose a silicon-based wavelength diplexer in the form of a bullet-shaped structure using subwavelength grating (SWG) for 1.55 and 2 μm wavelengths based on the inverse design. Since the embedded SWG can significantly shorten the beat length corresponding to the two wavelengths, the device length can be shortened by adjusting the effective refractive index while maintaining the device with low insertion loss (IL) and high contrast (C). When the particle swarm optimization (PSO) algorithm is used to optimize the relevant parameters of the wavelength diplexer, the optimal length of 12.6 μm is obtained. The results show that the IL and C of the wavelength diplexer successfully designed by PSO are 0.19/0.54 dB and 21.21/21.33 dB at 1.55/2 μm, respectively, and its bandwidth is greater than 118/85 nm when C > 15dB and IL < 1dB. The inverse design has been proved to be effective and can be extended to other device designs.