LiNbO/sub 3/ optical waveguide fabrication by high-temperature proton exchange

An efficient method, the high-temperature proton exchange (HTPE), to fabricate high-quality LiNbO/sub 3/ optical waveguides is studied. The new proton exchange 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 /spl alpha/-phase waveguides are fabricated by SPE. This phase presents the same crystalline structure as that of LiNbO/sub 3/ and, as expected, maintains the excellent nonlinear and electrooptical properties of the bulk material. The kinetics of HTPE is studied.