Parametric amplification of Raman-inactive lattice oscillations induced by two-color cross-beam excitation.
The second-order Raman bands of SrTiO(3) are excited under two-color cross-beam configuration using femto-second laser pulses. Raman-inactive one-phonon waves are generated by the coherently excited large amplitude two-phonon wave. The one-phonon waves are observed as a train of visible light spots, the frequency steps of which are coincident with the frequencies of the one-phonon modes. In order to understand the mechanism, a model of three-wave interaction among one two-phonon wave and two one-phonon waves is proposed.
Takahashi
Jun-Ichi
J