| 摘要 |
PURPOSE:To obtain an optical circuit of a small size and simple constitution wherein the propagation phase constants of a TE wave and a TM wave are coincident by providing a regulating film on the top surface of a waveguide layer in which double refraction is generated. CONSTITUTION:A regulating film 3 is provided on a waveguide layer 2 in which double refraction is generated. The addition of the regulated film contributes to an increase in the equivalent refractive indices nTE and nTM of a TE wave and a TM wave, and since the nTM is increased at a higher rate than that of the nTE with a corresponding decrease in DELTAneff=nTE-nTM, the position where the phases match moves to the t'0 on the left side as shown by a broken line and the extent of the movement can be selected by the size in the thickness t' of the regulating film. The errors in setting of the film thickness or double refraction generated in the manufacturing stage of the waveguide layer are corrected by setting the thickness of the regulating film suitably, whereby the difficulty in the manufacturing stage of the conventional waveguide is eliminated and reliability is improved. |
