Complex dissipation coupling engineered photon blockade with a microresonator waveguide

Photon blockade is a single-photon generation method based on strong nonlinearities. In this Letter, we propose a system with emission and pumping modes to realize photon blockade by a microring resonator-waveguide system. We find that Friedrich-Wintgen bound states in the continuum (BICs) emerge from destructive quantum interference by engineering complex dissipation coupling. Consequently, photon blockade can be observed due to the high quality factor of one BIC eigenmode and the reduction of effective decay when the Friedrich-Wintgen condition is satisfied. Moreover, we show that photon blockade can also occur at a small Kerr nonlinearity. We also investigate the influences of phase and strength in dissipation coupling on photon blockade.