ENERGY-TRANSFER CHARACTERISTICS OF PHOTOREFRACTIVE CONTRADIRECTIONAL 2-WAVE MIXING

Expressions of the coupling constant for contradirectional two-wave mi xing (CTWM) have been derived. The calculations show that the energy t ransfer in CTWM has some unique characteristics different from the for ward two-wave mixing (FTWM), in which the energy transfer direction is dependent on the two beam orientations with respect to the crystal po lar axis and the sign of the light-induced carriers as well as the ele ctro-optic coefficients. As a result, the CTWM can have a reverse ener gy transfer direction to the FTWM under a certain condition. The exper imental results in two typical crystals of Rh-doped BaTiO3 and in Ce-d oped strontium barium niobate (SBN:Ce) demonstrate the theoretical inv estigations very well. (C) 1997 Elsevier Science B.V.