Fast thermo-optic switching on silicon nitride platform through parity-time symmetry breaking

TL;DR

This paper introduces a rapid thermo-optic switch on a silicon nitride platform utilizing parity-time symmetry breaking, achieving fast switching with low loss and minimal thermal cross-talk.

Contribution

It presents a novel low-loss, fast thermo-optic switching mechanism on silicon nitride using parity-time symmetry breaking and integrated metal heaters.

Findings

Achieved 8.5 μs rise time for π phase shift.

Demonstrated low insertion loss of 0.39 dB.

Investigated thermal cross-talk effects.

Abstract

This work demonstrates a fast thermo-optic switching mechanism on silicon nitride on insulator platform leveraging parity-time symmetry breaking. The cladding-free design enables low-loss optical propagation in a partially metal-covered waveguide, with the same metal layer serving as an integrated heater for rapid phase tuning. The fabricated device exhibits an 8.5 {\mu}s rise time for a {\pi} phase shift, despite the weak thermo-optic coefficient in silicon nitride. Additionally, the impact of thermal cross-talk is investigated and an insertion loss as low as 0.39 dB for a 100-{\mu}m-long heater-waveguide section is demonstrated.