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 enables one to coherently drive and detect in the temporal domain, non-symmetric phonon modes from crystals. The use of homodyne and heterodyne detections is discussed and the technique applied to E-symmetry phonon-polaritons in PbTiO3 uniaxial crystal. Results are consistent with a splitting of the lowest polariton branch, at very small wavevector value, which provides further evidence of the high anharmonicity of this perovskite ferroelectric. Copyright (C) 1996 Published by Elsevier Science Ltd