We determine the conical half-angle at which a weak, loosely focused Bessel–Gauss beam of fixed focal intensity and confocal parameter is most efficient at generating a given harmonic in a gaseous target of arbitrary density profile. Simple analytical results are compared with fully numerical calculations for hydrogen, xenon, and rubidium. The variation of the conversion efficiency with the conical half-angle is shown to depend on the properties of the medium only through the macroscopic dispersion.
© 1999 Optical Society of America
C. F. R. Caron and R. M. Potvliege, "Optimum conical angle of a Bessel–Gauss beam for low-order harmonic generation in gases," J. Opt. Soc. Am. B 16, 1377-1384 (1999)