Abstract

Efficiency optimization of second harmonic generation (SHG) with freely propagating beams in bulk nonlinear crystals is of primary importance in a number of applications. In one of the early works on SHG Boyd and Kleinman found the gaussian beam that maximizes the efficiency as a result of the best compromise between the beam focalization, which enhances the efficiency, and the diffractive spread, which reduces it. More recently it has been suggested [1] that “non diffracting” Bessel beams could generate second harmonic more efficiently than gaussian ones, while other authors [2] disagree with this conclusion. In any case, a question remains open: what is the beam that, for given crystal and beam power, gives the absolute maximum of the SHG efficiency?

© 2000 IEEE