| 摘要 |
PURPOSE:To reduce the invasion of a base transmission mode into an optical waveguide, to improve an S/N and to omit a thick piezoelectric base by setting up the refractive index of the optical waveguide to a value less than that of the piezoelectric base. CONSTITUTION:Parallel beams radiated from a semiconductor laser 3 through the optical waveguide and an optical waveguide lens 4 formed on an vapor deposited piezoelectric thin film 2 formed on the piezoelectric base 1 are diffracted in accordance wit a surface acoustic wave 11 based on a transducer 6, a dumper 7, etc., to be driven by an electrical signal. The diffracted light is detected by a photodetector array 8 through an optical waveguide lens 5 or the like. The refractive index of the optical waveguide is simply reduced in the depth direction and the refractive index of the base 1 is larger than that of the optical waveguide at the part in contact with the base 1, so that the invasion of the base transmission mode into the optical waveguide is reduced and the S/N is improved. Consequently, it is unnecessary to use a thick piezoelectric base and the economical efficiency of a spectrum analyzer is improved. |
