Design of an ultra-compact, energy-efficient non-volatile photonic switch based on phase change materials

The on-chip photonic switch is a critical building block for photonic integrated circuits (PICs) and the integration of phase change materials (PCMs) enables non-volatile switch designs that are compact, low-loss, and energy-efficient. Existing switch designs based on these materials typically rely on weak evanescent field interactions, resulting in devices with a large footprint and high energy consumption. Here we present a compact non-volatile 2 by 2 switch design leveraging optical concentration in slot waveguide modes to significantly enhance interactions of light with PCMs, thereby realizing a compact, efficient photonic switch. To further improve the device's energy efficiency, we introduce an integrated single-layer graphene heater for ultrafast electrothermal switching of the PCM. Computational simulations demonstrate a 2 by 2 switch 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.