Ultra-high order ring resonator system with sharp transmission peaks

We propose a relay ring resonator structure which comprises multiple cascaded microring resonators, in which the drop waveguide of a microring resonator is also the input waveguide of the subsequent microring resonator, and so forth. Thus, the transmission response of the relay ring resonator structure has sharp peaks, high out-of-band rejection ratios, and long group delays. A relay ring resonator structure comprising 90 microrings is fabricated on silicon nitride wire waveguides. The simulation and experimental results are in good agreement.