Numerical modeling of an integrated non-volatile reflector switch and mode converter switch based on a low loss phase change material (Sb2Se3) in SiN platforms

Abstract

Programmable integrated photonics is an emerging research field due to its range of applications, from data processing to computing. Phase change materials (PCMs) on waveguides provide enormous flexibility for programmable integrated photonics. These materials show a large contrast in the optical properties (such as refractive index and optical loss) between the two stable states (i.e., amorphous to crystalline) of the PCM. These states are reversible and reproducible with an external stimuli which could be optical, thermal or electrical. Their non-volatile behavior allows PCMs to serve as an active layer for programmable photonics. In this work, we investigate hybrid device architectures utilizing the non-volatile properties of PCMs for integrated programmable photonics in a Si3N4 platform. FDTD modeling was carried out to design two configurations of non-volatile reconfigurable switches: (1) A non-volatile reconfigurable reflector switch consisting of a photonic crystal (PhC) slab waveguide and having a thin layer of Sb2Se3 on top of the waveguide and (2) 1×2 mode converter switch. In the case of a non-volatile reconfigurable reflector switch, the reflectivity of the waveguides is controlled by shifting the mode-gap of the photonic crystal slab waveguide by changing the phase of the PCM. It has applications as a reconfigurable reflective filter in the optical communication system and on-chip smart Bragg mirror. Non-volatile broadband directional switches provide a new paradigm for designing programmable multifunctional nanophotonics, which works in the same way as electronic field-programmable gate arrays. A 1×2 mode converter switch — based on Sb2Se3 as a clad layer on a coupling waveguide of a directional coupler — is proposed. The optical switches proposed in this paper offer very low optical insertion loss (∼ 0.5 dB), low coupling length (∼ 12 µm), broadband operation (∼ 80 nm), small cross talk (∼ 16 dB), and zero static power consumption.