Ultra-Efficient DC-gated all-optical graphene switch

TL;DR

This paper introduces a highly efficient, electrically tunable all-optical graphene switch integrated into silicon waveguides, achieving low energy consumption and high extinction ratio suitable for photonic computing.

Contribution

The work presents a novel design of an integrated graphene switch with enhanced absorption and electrical tunability, reducing switching energy and voltage requirements.

Findings

High extinction ratio of 10.3dB achieved

Switching energy as low as 79fJ/bit

Low insertion loss of less than 0.7dB

Abstract

The ultrafast response and broadband absorption of all-optical graphene switches are highly desirable features for on-chip photonic switching. However, because graphene is an atomically thin material, its absorption of guided optical modes is relatively low, resulting in high saturation thresholds and switching energies for these devices. To boost the absorption of graphene, we present a practical design of an electrically-biased all-optical graphene switch that is integrated into silicon slot waveguides, which strongly confine the optical mode in the slotted region and enhance its interaction with graphene. Moreover, the design incorporates a silicon slab layer and a hafnia dielectric layer to electrically tune the saturation threshold and the switching energy of the device by applying DC voltages of <0.5 V. Using this device, a high extinction ratio (ER) of 10.3dB, a low insertion loss (IL) of <0.7dB, and an ultra-efficient switching energy of 79fJ/bit at 0.23V bias are attainable for a 40um long switch. The reported performance metrics for this device are highly promising and are expected to serve the needs of next-generation photonic computing systems.