Nested silicon-on-insulator Vernier effect microring resonators

Vernier effect, series-coupled microring resonators (MRRs) are used to extend the free-spectral-range (FSR) of MRRs. In this work we demonstrate integrating two MRRs in a compact Vernier configuration (compact as compared to previously demonstrated Vernier effect devices). our design was realized by using two waveguide crossings to form a major, outer ring that was coupled to a minor ring nested within the major ring. The ratio of the path length of the major ring to the path length of minor ring was 5:2. The spectral response of the device had an FSR of 27.94 nm, a drop port 3 dB bandwidth of 0.87 nm, a minimum extinction ratio of 16.1 dB, a minimum interstitial peak suppression of 10.6 dB, and a footprint of only 540 μm² .