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.