A novel low-threshold amplification scheme for bichromatically coupling three upper states including a metastable state is investigated. Based on model calculations, it is possible to amplify coherent vacuum-ultraviolet emission in Kr gases without population inversion at the probed transition. In this system, therefore, media that are the same as those used for lasing (e.g., Kr) can be used as the incoherent pumping source. The low-threshold amplification is attained when the spontaneous emission at the probed transition is modulated through population trapping in the upper states by two intense coupling lasers. The possibility of continuous amplification of vacuum-ultraviolet emission in this model is discussed.
© 1998 Optical Society of America
(140.7240) Lasers and laser optics : UV, EUV, and X-ray lasers
(190.4410) Nonlinear optics : Nonlinear optics, parametric processes
(270.4180) Quantum optics : Multiphoton processes
(270.6620) Quantum optics : Strong-field processes
Masahiro Takeoka, Tsuneo Nakata, and Fumihiko Kannari, "Low-threshold amplification of vacuum-ultraviolet radiation in bichromatically driven Kr gases," J. Opt. Soc. Am. B 15, 2967-2974 (1998)