Light propagation through closed-loop atomic media beyond the multiphoton resonance condition

摘要: The light propagation of a probe field pulse in four-level double-lambda type system driven by laser fields that form closed interaction loop is studied. finite frequency width the requires time-dependent analysis beyond multiphoton resonance assumption. We apply Floquet decomposition to equations motion solve this problem and identify different scattering processes contributing medium response. find response oscillating phase with phase-independent. dependence arises from coupling into mode at which general differs frequency. In particular for short pulses large width, inducing contour may lead distortion shape via phase-sensitive scattering. Finally, we demonstrate both nonclosed configuration allow sub- superluminal small absorption or even gain, where one Rabi frequencies acts as control parameter enables switch between propagation.