Tunable nonlinear coherent perfect absorption in cavity QED

We propose and analyze a scheme for tunable coherent perfect absorption (CPA) and near-perfect reflection (near CPR) in a three-level A-type atom-cavity system. With electromagnetically-induced-transparency-type interference induced by a coherent coupling laser, it provides a method of tunable near CPR at two-photon resonance. By virtue of different coupling strengths, CPA can be tuned from the linear regime to the nonlinear or bistable regime at a fixed input-field frequency. In addition, the CPA regime can be switched to the near-CPR regime with variable linear absorption or gain by an incoherent pump field. This work suggests a mechanism for manipulation on perfect absorption and reflection theoretically which can potentially be applied to logical gates and optical switches for coherent optical computing and communication.