Holographic recording in planar Cu : H : LiTaO3 waveguides

Abstract

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