INTENSITY-DEPENDENT CHANGE OF THE POLARIZATION STATE AS A RESULT OF NONLINEAR PHASE-SHIFT IN TYPE-II FREQUENCY-DOUBLING CRYSTALS

The effect of an intensity dependent change of the polarization state of the fundamental wave involved in imbalanced type II frequency doubl ing is considered. The effect is described and derived by uc; as analy tical formulae expressed in terms of elementary functions. We show (i) that a type II second harmonic generation crystal can be considered a s a wave plate with intensity dependent retardation and (ii) that the system ''polarizer-type II frequency doubling crystal-analyser'' has s trong pulse shortening and self-induced transparency. (C) 1997 Elsevie r Science B.V.