Anisotropy of the optical poling of glass

A giant reversible increase (>~10³ times) of the optical second-order harmonic's (SH) absorption by optical poling of oxide glass was found. The SH's absorption kinetics manifested anisotropy with respect to polarization of the pumping (poling) light. The observed absorption exerts the influence of optical poling on the observed processes and leads to a limitation of the maximum value of the photoinduced SH output in oxide glass. An explanation of the observed phenomenon is given. It was shown that the observed process is a typical steady-state effect with participation of trapping levels, and its polarized dependence is caused by the photoinduced anisotropy of the photocarrier diffusion and by the electron-phonon anharmonic interaction.