Integrated Fabry-Perot cavities as a mechanism for enhancing micro-ring resonator performance

TL;DR

This paper demonstrates a method to significantly enhance the quality factor and extinction ratio of integrated micro-ring resonators by embedding them in a Fabry-Perot cavity formed with Sagnac loop reflectors, combining theoretical analysis and experimental validation.

Contribution

The paper introduces a novel integrated Fabry-Perot cavity design using cascaded Sagnac loop reflectors to improve micro-ring resonator performance, validated through fabrication and experiments.

Findings

Up to 11-fold increase in Q factor achieved.

8 dB enhancement in extinction ratio observed.

Performance improvements verified through varied structural parameters.

Abstract

We propose and experimentally demonstrate the enhancement in the filtering quality (Q) factor of an integrated micro-ring resonator (MRR) by embedding it in an integrated Fabry-Perot (FP) cavity formed by cascaded Sagnac loop reflectors (SLRs). By utilizing coherent interference within the FP cavity to reshape the transmission spectrum of the MRR, both the Q factor and the extinction ratio (ER) can be significantly improved. The device is theoretically analyzed, and practically fabricated on a silicon-on-insulator (SOI) wafer. Experimental results show that up to 11-times improvement in Q factor, together with an 8-dB increase in ER, can be achieved via our proposed method. The impact of varying structural parameters on the device performance is also investigated and verified by the measured spectra of the fabricated devices with different structural parameters.