Tuneable Acoustic-optic Reflection Filters in LiNbO sub 3 Without a Doppler Shift.

Tuneable, narrow-band wavelength filters with single-mode waveguides are of great interest for use with extended cavity semiconductor lasers as tuneable, intra-cavity wavelength filters. In this paper we propose an acousto-optic filter in LiNbO sub 3 without the Doppler shift, which is normally present in acousto-optic filters and which is undesirable as an intra-cavity element. This tuneable filter has a significantly wider tuning range than previously demonstrated electro-filters. Crystal symmetry and acoustic power considerations are treated in detail.