Ultra-compact optical switch based on Sb2Se3-assisted PhC-like subwavelength structures

Ultra-compact optical switch is a crucial module for densely integrated on-chip network. In recent years phase-change materials (PCMs) enable design of ultra-compact reconfigurable devices due to their drastic refractive index change during phase transition. In this work we inverse design a photonic-crystal-like (PhC-like) subwavelength optical switch assisted by novel ultralow loss PCM: Sb2Se3. At amorphous state the refractive index of Sb2Se3 is similar to that of silicon, so the device work as a MMI and light outputs at output port 2. At crystalline state the refractive index of Sb2Se3 increases to 4.05 and the subwavelength structure guides light to output port 1. The proposed switch has a compact footprint of 2.75 × 16 μm2. At the center wavelength of 1550nm, the simulated insertion losses and crosstalks are 0.36 dB, -44.36 dB, 0.49 dB, and -40.37 dB under amorphous and crystalline states respectively.