Spectral Engineering with Coupled Microcavities: Active Control of Resonant Mode-Splitting

TL;DR

This paper presents a novel active control method for resonant mode-splitting in coupled microcavities, enabling reconfigurable spectral shaping with minimal undesired resonance shifts using low power microheaters.

Contribution

It introduces a control mechanism that actively manages counter-traveling modes to achieve widely tunable mode-splitting while suppressing resonance shifts, advancing nanophotonic device tuning capabilities.

Findings

Achieved 80 GHz mode-splitting with low power microheaters

Demonstrated transition from large splitting to single-notch resonance

Resonance-shift limited only by thermal crosstalk

Abstract

Optical mode-splitting is an efficient tool to shape and fine-tune the spectral response of resonant nanophotonic devices. The active control of mode-splitting, however, is either small or accompanied by undesired resonance shifts, often much larger than the resonance-splitting. We report a control mechanism that enables reconfigurable and widely tunable mode-splitting while efficiently mitigating undesired resonance shifts. This is achieved by actively controlling the excitation of counter-traveling modes in coupled resonators. The transition from a large splitting (80 GHz) to a single-notch resonance is demonstrated using low power microheaters (35 mW). We show that the spurious resonance-shift in our device is only limited by thermal crosstalk and resonance-shift-free splitting control may be achieved.