Anisotropy of UV-induced degradation of LBO crystal

We investigated ultraviolet-induced bulk degradation of nonlinear optical crystal LBO. We measured time of the defect formation induced by long-term high power pulsed laser radiation at 355 nm. Strong dependence on the directions of the beam and its polarization was found. We also measured temperature dependence of the crystal lifetime. Model of crystal degradation under higher order harmonics generation is suggested.