HOLOGRAPHIC RECORDING IN PLANAR CU-H-LITAO3 WAVE-GUIDES

Photorefractive planar waveguides in LiTaO3 are fabricated by a proton exchange and a successive copper exchange from melts, containing eith er Cu+ or Cu2+ ions. The influence of different fabrication steps on r efractive index profiles, hydrogen content, optical absorption, and wa veguide transparency is investigated. With holographic methods dark an d photoconductivity, holographic sensitivity, and light-induced refrac tive index change are measured. By the additional copper exchange the steady-state diffraction efficiency of holographic gratings in the wav eguides is increased from 0.005 to 81%. Here the crucial influence of both, Cu valence state and hydrogen concentration on the holographic s ensitivity is demonstrated.