Ultraviolet irradiation effect on the third-order optical nonlinearity of CuCl-microcrystallite-doped glass

We investigate the effect of irradiation by a UV pulse laser on the third-o rder optical nonlinearity of CuCl-microcrystallite-doped glass as a functio n of the irradiation's shot number, energy density per pulse, and wavelengt h. The response time tau is estimated from the luminescence decay time of t he CuCl excitons. The absolute value of the third-order nonlinear susceptib ility chi((3)) is measured by degenerate four-wave mixing. Values of both t au and chi((3)) decrease after UV irradiation. The figure of merit for the optical nonlinearity, chi((3))alpha tau, where alpha is the absorption coef ficient, is almost constant before and after UV irradiation and is approxim ately 500 esu cm s(-1) in the case of 8-nm CuCl microcrystallites. This val ue is 1 order of magnitude larger than that of CdSxSe1-x-microcrystallite-d oped glasses. The mechanism by which tau and chi((3)) are decreased is disc ussed, considering defects levels formed at the interface between CuCl micr ocrystallites and glass matrix. (C) 2000 Optical Society of America [S0740- 3224(00)00604-4] OCIS codes: 190.4720, 190.4400, 160.2750, 160.4330, 160.47 60, 350.3450.