Wavelength dependence of photoreduction of Ag+ ions in glasses through themultiphoton process

We have investigated the wavelength dependence of the photoreduction of Ag ions in glass irradiated by visible femtosecond pulses. These pulses, issu ed at wavelengths ranging from 400 to 800 nm, were nonresonant with the gla ss absorption. In this article, a relationship between threshold powers, wa velengths, and linear and nonlinear refractive indices is described. The no nlinear refractive index of Ag+-doped glass was measured by an optical Kerr shutter method. The wavelength dependence of threshold powers of the photo reduction is explained by considering linear and nonlinear refractive indic es. The mechanism of the photoreduction is also discussed. (C) 2000 America n Institute of Physics. [S0021-8979(00)05615-2].