Modeling Compact Non-Volatile Photonic Switching Based on Optical Phase Change Material and Graphene Heater

Abstract

On-chip photonic switches are the building blocks for programable integrated circuits (PICs) and the integration of phase change materials (PCMs) enables promising designs which are compact, non-volatile, and efficient. However, conventional PCMs such as Ge₂Sb₂Te₅ (GST) introduce significant optical absorption loss, leading to elevated insertion losses in devices. Current approaches, compensating for this loss through weak evanescent light-PCM interactions, result in larger footprint devices. A compact non-volatile 2 × 2 switch design is introduced, leveraging optical concentration in slot waveguide modes to significantly enhance interactions of light with PCM, thereby realizing a compact, efficient photonic switch. The crystalline-amorphous phase transitions are driven by an integrated single-layer graphene heater, providing high electro-thermal efficiency, low absorption loss, and rapid switching speed. Computational simulations demonstrate reversible phase transitions of Sb₂Se₃ facilitating 2 working states with crosstalk (CT) down to -24 dB at 1550 nm wavelength and more than 55 nm 0.3 dB insertion loss (IL)bandwidth. The proposed photonic switch architecture can constitute the cornerstone for next-generation high-performance reconfigurable photonic circuits.