Kumar Rakesh Ranjan, Wu Xinru, Tsang Hon Ki
Opt Lett. 2020 Mar 15;45(6):1289-1292. doi: 10.1364/OL.384187.
We describe the use of cascaded second-order coupled-resonator optical waveguide (CROW) tunable filters to achieve one of the highest reported measured extinction ratios of $ {\gt} {110};{\rm dB}$>110dB. The CROW filters were used to remove the pump photons in spontaneous four-wave mixing (SFWM) in a silicon waveguide. The SFWM generated quantum-correlated photons that could be measured after the cascaded CROW filters. The CROW filters offer a compact footprint for use in monolithic quantum photonic circuits.
