J. Olivares et Jm. Cabrera, GUIDED MODES WITH ORDINARY REFRACTIVE-INDEX IN PROTON-EXCHANGED LINBO3 WAVE-GUIDES, Applied physics letters, 62(20), 1993, pp. 2468-2470
A method is proposed and demonstrated to fabricate guiding layers on o
rdinary refractive index in proton exchanged LiNbO3 waveguides. The pr
ocess consists of performing a reverse exchange in a melt very rich in
lithium on a substrate previously exchanged in normal benzoic acid. L
ayers supporting several modes with ordinary polarization are easily o
btained. Losses for these modes have been found to be below 0.7 dB/cm.
Together with the increase of ordinary index, a decrease of the extra
ordinary one is obtained so that buried modes can be guided with this
polarization. The influence on the reverse process of the exchange tem
perature, the substrate cut, and the melt composition is studied.