Design and optimization of optical modulators based on graphene-on-silicon nitride microring resonators

TL;DR

This paper presents a novel graphene-on-silicon nitride microring resonator design that achieves high modulation depth by optimizing geometrical parameters and graphene coverage, enhancing optical modulation performance.

Contribution

It introduces a systematic approach to optimize graphene-on-SiNx microring resonators for high modulation depth and fabrication tolerance, combining electro-absorptive and electro-refractive effects.

Findings

Achieved over 40 dB modulation depth.

Optimized geometrical parameters for loss tunability and index variation.

Demonstrated large fabrication tolerance.

Abstract

In order to overcome the challenge of obtaining high modulation depth due to weak graphene-light interaction, a graphene-on-silicon nitride (SiNx) microring resonator based on graphene's gate-tunable optical conductivity is proposed and studied. Geometrical parameters of graphene-on-SiNx waveguide are systematically analyzed and optimized, yielding a loss tunability of 0.04 dB/{\mu}m and an effective index variation of 0.0022. We explicitly study the interaction between graphene and a 40-{\mu}m-radius microring resonator, where electro-absorptive and electro-refractive modulation are both taken into account. By choosing appropriate graphene coverage and coupling coefficient, a high modulation depth of over 40 dB with large fabrication tolerance is obtained.