The substrate which possesses the optical communication system null acousto-Optics acoustooptics effect which uses the optical

摘要

PROBLEM TO BE SOLVED: To embody an efficient plane surface acoustic wave(SAW) waveguide and to increase the degree of freedom in design for control of filter characteristics by forming a thin film on the surface of a substrate and forming the substrate surface as a ridge structure. ;SOLUTION: The transparent thin film 18 of SiO₂, etc., is formed in approximately the same direction as the direction of optical waveguides 11, 12 for propagation in an approximately X- or Y-axis direction formed within the surface of the LnNbO₃ substrate in such a manner that the substrate surface is formed to the ridge shape. Namely, the optical waveguides 11, 12 extending in the y-axis direction are formed on the x-cut LnNbO₃ substrate 10 and a transducer 15 for generating SAW is formed thereon. A SAW absorber consisting of a resist is formed between the light input side of the LnNbO₃ substrate 10 and the transducer 15. The thin film 18 for the SAW waveguide consisting of the SiO₂ film having the refractive index lower than the refractive index of the LnNbO₃ substrate is formed on the waveguide behind the same. The SAW absorber 20 consisting of the resist is formed in front of an electrode and at the final point of the thin film 18 for the SAW waveguide.;COPYRIGHT: (C)1999,JPO