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-order optical nonlinearity of CuCl-microcrystallite-doped glass as a function of the irradiation's shot number, energy density per pulse, and wavelength. The response time tau is estimated from the luminescence decay time of the CuCl excitons. The absolute value of the third-order nonlinear susceptibility chi((3)) is measured by degenerate four-wave mixing. Values of both tau and chi((3)) decrease after UV irradiation. The figure of merit for the optical nonlinearity, chi((3))alpha tau, where alpha is the absorption coefficient, is almost constant before and after UV irradiation and is approximately 500 esu cm s(-1) in the case of 8-nm CuCl microcrystallites. This value is 1 order of magnitude larger than that of CdSxSe1-x-microcrystallite-doped glasses. The mechanism by which tau and chi((3)) are decreased is discussed, considering defects levels formed at the interface between CuCl microcrystallites and glass matrix. (C) 2000 Optical Society of America [S0740-3224(00)00604-4] OCIS codes: 190.4720, 190.4400, 160.2750, 160.4330, 160.4760, 350.3450.