Abstract: A nonlinear optical mixer produces coherent vacuum ultraviolet radiation. A cell contains a gas mixture of xenon and a phase-matching gas. A pump laser beam selectively excites the two-photon transition in the xenon gas. A mixing laser beam is also directed towards the gas mixture. Coherent vacuum ultraviolet radiation is produced by four wave mixing of the pump and mixing laser beams. The phase-matching gas, for example mercury vapor, is used to achieve phase matching of the four wave mixing. The coherent vacuum ultraviolet radiation preferably has a wavelength of approximately 157.6 nm (the molecular fluorine line) or 121.6 nm (the Lyman-&agr; hydrogen line). In a preferred embodiment, the two laser beams are loosely-focused.

Abstract: A nonlinear optical mixer produces coherent vacuum ultraviolet radiation. A cell contains a gas mixture of xenon and a phase-matching gas. A pump laser beam selectively excites the two-photon transition in the xenon gas. A mixing laser beam is also directed towards the gas mixture. Coherent vacuum ultraviolet radiation is produced by four wave mixing of the pump and mixing laser beams. The phase-matching gas, for example mercury vapor, is used to achieve phase matching of the four wave mixing. The coherent vacuum ultraviolet radiation preferably has a wavelength of approximately 157.6 nm (the molecular fluorine line) or 121.6 nm (the Lyman-&agr; hydrogen line). In a preferred embodiment, the two laser beams are loosely-focused.

Abstract: A method for producing electromagnetically induced transparency (EIT) in atoms with hyperfine structure. EIT is the phenomenon in which a material (e.g. lead vapor) becomes transparent to a first electromagnetic frequency (a probe beam) when exposed to a second electromagnetic frequency (a coupling beam). In the present invention, the atom has hyperfine split energy levels. In the method of the present invention, the coupling and probe beams are tuned to transitions between the centers of gravity (COGs) of the hyperfine split levels. This allows high transparencies to be achieved in high opacity materials. Also, the present method can produce EIT in isotopically mixed materials. This is because the COGs of hyperfine split levels (in nuclear spin.notident.0 atoms) are generally coincident with nonhyperfine split levels (in nuclear spin=0 atoms). The method of the present invention is directly applicable to nonlinear sum and difference frequency generation.