BEAM-COUPLING IN TETRAGONAL POTASSIUM TANTALATE-NIOBATE CRYSTALS

Beam-coupling is investigated in a nominally pure tetragonal potassium Tantalate-Niobate (KTN) crystal as a function of external electric fi eld, spatial frequency and light wavelength. The variation of these pa rameters leads to a change of the direction of energy transfer between the two recording beams. The experimental results can be consistently described by a one-center charge-transport model taking into account electron and hole contributions to photoconductivity and space-charge limitations due to the available trap density.