White-light cavity with multiple broad bands based on tunable negative dispersion in a multi-level system

Abstract

We propose a scheme for the generation of a white-light cavity with multiple broad frequency bands by using an incoherent pumped multi-level atomic system. Owing to the destructive quantum interference induced by the coherent coupling fields, multiple negative dispersion regions with a broadband characteristic can be achieved within the transparency windows, which result from resonant gain suppression. By simply adjusting the control fields, the negative material dispersion compensates the normal dispersion of cavity in the transparency regions, so we can obtain a white-light cavity with multiple wide frequency bands. Moreover, the cavity linewidth depends explicitly on the incoherent pumping rate and gas density. When the system interacts with more coherent coupling fields, we anticipate that more bands will be generated in the cavity transmission spectrum. The proposed scheme can find applications in many fields, such as a wide-band optical switch for multiple signals.