Abstract

It is of interest to use nonlinear optical materials in a wavelength domain close to the absorption band, in order to increase the nonlinear coefficient value of the material [1]. However, this absorption should appear at a multiphoton level, because single photon absorption gives rise to high optical attenuation of the pump beam. This concept is mainly applied in third order nonlinear experiments [2], for which working near half the band gap leads to high χ⁽³⁾ coefficient without strong absorption of the pump beam.

© 1993 Optical Society of America