Resonant frequency doubling in vapors and gases

A theoretical analysis is made of the possibility of doubling the frequency of laser pump radiation in a gaseous medium which absorbs resonantly the second harmonic and is subjected to an electrostatic field. Frequency conversion coefficients are calculated for gases composed of polar and nonpolar molecules. The latter can be used in frequency doubling in the vacuum ultraviolet range. Estimates of the coefficient of conversion of the pump radiation into its second harmonic give values of the order of 10% (in respect of the power). Some transitions in vapors and gases, suitable for resonant frequency doubling of visible and ultraviolet radiation are identified. In particular, the possibility of generating radiation at λ=59.3 nm in neon is considered for the case when the pump radiation is the ninth harmonic of a neodymium laser.