Controlling optical response to charged particles in EIT media

There is a good tunability of the optical response of atomic media in electromagnetically induced transparency (EIT) states. In the weak-field approximation, features of the optical response in 3-level atoms include low absorption, strong nonlinearity and slow light for frequencies in a transparency window centered on the transition frequency with KHz bandwidth. Theoretical results show significant variation of pulse properties such as the group velocity and spectral chirp with the atomic system and dressing field parameters. This high sensitivity of the susceptibility to small changes in the parameters implies the pulse spectrum can be controlled with very weak fields probing the transitions. In this work, the detection of perturbative effects in the medium is studied, specifically from a train of high energy charged particles passing through the medium. A control scheme is developed to allow for continuous trapping of spectrally tuned Cherenkov radiation in the medium along a narrow group cone to determine properties of the charge train through change of the optical response.