High efficiency frequency up-conversion enhanced by electromagnetically induced transparency

Electromagnetically induced transparency (EIT) can enhance the conversion efficiency of a resonant four-wave mixing scheme. This is demonstrated for a scheme in Kr resulting in the generation of a field at 123.6 mm. The absolute VUV radiation yield was measured using a calibrated photodiode in the limit of a large density-length product. Energies of similar to 30 nJ per pulse were produced, with an energy conversion efficiency from the coupling field of similar to 1%. Higher yields are thought to be achievable by the use of a transform limited UV pulse of the same duration as the coupling field and by increasing the coupling laser intensity and the path length in the medium.