LiNbO3 optical waveguide fabrication by high-temperature proton exchange

An efficient method, the high-temperature proton exchange (HTPE), to fabric ate high-qualitly LiNbO3 optical waveguides is studied. The new proton exch ange source, the stearic acid diluted by lithium stearate, is proposed for HTPE process. The known soft proton exchange (SPE) process can be realized by HTPE. There are no phase transitions when the ct-phase waveguides are fa bricated by SPE, This phase presents the same crystalline structure as that of LiNbO3 and, as expected, maintains the excellent nonlinear and electroo ptical properties of the bulk material. The kinetics of HTPE is studied.