Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE
Tunable lossless slow and fast light in a four-level N-system
Irina V. Novikova, Eugeniy E. Mikhailov, Logan Stagg, Simon Rochester, Dmitry Budker
Abstract
We investigate the propagation of a weak probe laser field in a medium of warm Rb atoms, controlled with two strong resonant pump fields tuned to the D1 and D2 optical transitions to form an N-scheme arrangement. We have shown theoretically that four-wave mixing has a profound effect on the probe-field group velocity and absorption, allowing the probe-field propagation to be continuously tuned from superluminal to slow-light regimes with amplification. We have also identified the experimental conditions for observation of such tunable slow-to-fast light regime (continuously through the point of zero group index) with positive probe-field gain, and demonstrated that the spectral range corresponding to the zero group index can be tuned by controlling the power of one of the pump laser.