The probe response in four-level inverted-Y configuration showsgainwithout population inversionin presence of microwave field.At on-resonant probe field, switching between superluminal and subluminal probe propagation under the influence of microwave field is discussed in details.Both the bandwidth and sharpness of optical switching can easilybe controlled by varying the microwave power. The switching action improves immensely if the control transition is chosen to be a Rydberg transition. The transient behavior of the atomic system ultimately settles into probe gain under the influence of the microwave field.A way of transferring population to the highest excited state through the application of microwave field is also discussed.

四级倒Y形探针响应在微波场的存在下没有种群反转。在共振探针场中，详细讨论了在微波场的影响下超腔和亚腔探针传播之间的切换。通过改变微波功率可以很容易地控制光开关。如果将控制转换选择为里德伯格转换，则开关动作将大大改善。在微波场的影响下，原子系统的瞬态行为最终稳定在探针增益上。讨论了通过应用微波场将载量转移到最高激发态的方法。