Anomalous to normal dispersion nonlinear optical dephasing switch in electromagnetically induced transparency using a Kerr effect

The atomic decoherence effect (DE) on a Kerr nonlinear (KNL) electromagnetically induced transparency (EIT)is studied in a Δ system. The DE between the ground state hyperfine levels is caused by the dephasing rate γd which dramatically modifies the medium response. It controls the normal dispersive region which shows steep positive slopes for linear response at the line center while the nonlinear response experiences steep negative slopes for low γd. The microwave field strength and γd modify the nonlinear response from the anomalous dispersion to normal dispersion. The calculations show that room-temperature atoms are used to quantify the quantum interference (QI) on linear and nonlinear absorption with γd. The EIT spectrum explores the understanding of the subluminal and superluminal wave propagation of probe signal and this study opens a new pathway for the understanding of the QI devices and their nonlinearities based on EIT.