Silicon photonic filters based on cascaded Sagnac loop resonators

TL;DR

This paper demonstrates the design and fabrication of silicon photonic filters using cascaded Sagnac loop resonators, enabling versatile spectral shaping for integrated photonic applications.

Contribution

It introduces a novel approach to engineer spectral profiles of on-chip filters by controlling mode splitting in CSLR resonators, validated through theoretical and experimental results.

Findings

Achieved diverse filter shapes with high agreement between theory and experiment

Demonstrated mode splitting control for spectral profile engineering

Validated the effectiveness of CSLR resonators for multi-functional filtering

Abstract

We demonstrate advanced integrated photonic filters in silicon-on-insulator (SOI) nanowires implemented by cascaded Sagnac loop reflector (CSLR) resonators. We investigate mode splitting in these standing-wave (SW) resonators and demonstrate its use for engineering the spectral profile of on-chip photonic filters. By changing the reflectivity of the Sagnac loop reflectors (SLRs) and the phase shifts along the connecting waveguides, we tailor mode splitting in the CSLR resonators to achieve a wide range of filter shapes for diverse applications including enhanced light trapping, flat-top filtering, Q factor enhancement, and signal reshaping. We present the theoretical designs and compare the CSLR resonators with three, four, and eight SLRs fabricated in SOI. We achieve versatile filter shapes in the measured transmission spectra via diverse mode splitting that agree well with theory. This work confirms the effectiveness of using CSLR resonators as integrated multi-functional SW filters for flexible spectral engineering.