Anisotropies and intensity saturation of gray-tracking in KTiOPO4

We performed a complete quantitative study of anisotropy of gray-tracking induced in flux-grown KTiOPO4 by a polarized 532 nm pulsed laser, on the basis of transmission measurements before and after irradiation. The laser has. a 10 Hz repetition rate and a 6.5 ns half-width duration at 1/e2; its polarization is orientated parallelly or orthogonally to the polar axis (z-axis) of KTP. Two kinds of experiments were realized: measurement of transmission spectra from 300 nm to 3000 nm with a spectrophotometer which we modified for crystal measurements with polarized light; measurements of transmission of a polarized HeNe probe which is superposed on the 532 nm beam.