Compact asymmetric directional-coupler-based two-mode optical switch utilizing low loss Sb2Se3 phase-change material

Abstract

Mode division multiplexing (MDM) has provided a new trend in high capacity optical transmission systems. Some of the most important devices in MDM systems are multimode switches that can route signals simultaneously into different paths. In this work, a two-mode 1 × 2 optical switch based on an asymmetric directional coupler and using Sb2Se3 phase-change material is proposed with a compact size of 45 µ m × 6 µ m . This switch can route the fundamental and first transverse magnetic modes in a wide bandwidth in the third telecommunication window from 1535 to 1565 nm. According to the 3D finite-difference time-domain simulation results, this switch has a low insertion loss of 0.83 dB and cross talk of − 7.93 d B across the bandwidth in the “on” state. In addition, when the switch is off, it has suitable specifications in terms of insertion loss and cross talk with values lower than 0.29 dB and − 11.98 d B across the bandwidth, respectively.