SURFACE-ACOUSTIC-WAVE DISTRIBUTION AND ACOUSTOOPTIC INTERACTION IN PROTON-EXCHANGED LINBO3 WAVE-GUIDES

The efficiency of acoustooptic (AO) interaction in YZ-cut proton excha nged (PE) LiNbO3 waveguides is theoretically analysed by determining t he overlap between the optical and acoustic field distributions. The p resent analysis takes into account the perturbed SAW field distributio n due to the presence of the PE layer on the LiNbO3 substrate determin ed by the rigorous layered medium approach. The overlap is found to be significant upto very high acoustic frequencies of the order of 5 GHz , whereas in the earlier analysis by vonHelmolt and Schaffer [6] for d iffused waveguides, it was shown that the overlap integral rolls down to nearly zero at this high frequency range.