OPTICAL FILTER ADJUSTABLE BY ACOUSTOOPTICAL INTERACTION COLINEAR WITH SURFACE-WAVES

Acousto-optical mode convecters are the basic elements for a variety of integrated optical circuits. It has been demonstrated that efficient acousto-optical mode converters with a large tuning range and low drive power can be realized in a combined structure of acoustical and optical waveguides. We use an acoustical directional coupler to obtain a weighted coupling resulting in a theorical filter response with large sidelobe suppression. Nearly 100% TE/TM polarization conversion efficiency was achieved using only 3 mW of applied RF power in a 1.52 mum filter of 2 nm optical bandwidth on a cristal of LinbO3. Yet, the absolute sidelobe levels were significantly higher than expected. This is presumably due to nonuniformity in the effective birefringence of the optical waveguides.