Abstract

All unambiguous experiments on amplification without inversion (AWI) reported so far^1-3 rely on coherent population trapping (CPT) in the lower level of an atomic transition and demonstrate transient amplification of a probe field on the same transition. In order to make AWI useful, however, it is necessary lo obtain gain at frequencies sufficiently different from the one used in producing CPT. This is feasible in so-called "double-Λ"⁴- or "Raman"⁵- schemes. Moreover, the energy to be extracted from the medium by AWI should he deposited by an incoherent process.

© 1994 Optical Society of America