HOMODYNE AND HETERODYNE IMPULSIVE RAMAN KERR NONLINEARITIES IN CRYSTALS - APPLICATION TO E-SYMMETRY POLARITON MODES IN PBTIO3

We present a polarization sensitive pump-probe experiment which enable s one to coherently drive and detect in the temporal domain, non-symme tric phonon modes from crystals. The use of homodyne and heterodyne de tections is discussed and the technique applied to E-symmetry phonon-p olaritons in PbTiO3 uniaxial crystal. Results are consistent with a sp litting of the lowest polariton branch, at very small wavevector value , which provides further evidence of the high anharmonicity of this pe rovskite ferroelectric. Copyright (C) 1996 Published by Elsevier Scien ce Ltd