Abstract

Electromagnetically induced transparency (EIT) and its related effects have been studied extensively for over a decade. As early as 1990, Harris and co-workers predicted that resonantly-enhanced third-order susceptibility χ⁽³⁾ along with the low absorption from EIT could dramatically increase nonlinear optical frequency conversion. Since then, many experiments have demonstrated the enhancement of nonlinear optical processes (such as parametric processes and nondegenerate four-wave mixing) in multi-level atomic systems due to atomic coherence.^1-3 Kerr nonlinear effects can also be used for a variety of other useful applications such as cross-phase modulation for optical switching and self-phase modulation for generating optical solitons. Large nonlinear susceptibilities with low optical powers are desirable for realizing photon blockade, single-photon turnstile, and single-photon switching devices.^4,5

© 2001 Optical Society of America