Photorefractive properties of undoped lithium tantalate crystals for various composition

Holtmann F, Imbrock J, Baumer C, Hesse H, Kratzig E, Kip D

Zusammenfassung

Lithium tantalate crystals of compositions ranging from 48.3 mol \% to 50.0 mol \% lithium oxide are fabricated by vapor transport equilibration. Light-induced refractive index changes of the crystals are investigated with holographic methods at usual cw-laser intensities (approximate to10(5) W/m(2)) and with a single focused laser beam at high light intensities up to 2x10(7) W/m(2). In stoichiometric crystals the index changes are reduced by more than two orders of magnitude when compared with congruently melting ones. Simultaneously, the normalized photoconductivity sigma(ph)/I, where I is the light intensity, increases by nearly two orders of magnitude. Therefore, stoichiometric lithium tantalate is an attractive material for applications such as frequency conversion via quasi-phase matching. (C) 2004 American Institute of Physics.