| 摘要 |
PURPOSE:To reduce the total length and the loss in optical transmission by making integral two 3 dB couplers and an optical modulator in one optical waveguide composed of a linear portion. CONSTITUTION:If a voltage is impressed upon electrodes 7 and 8, the depthwise electric field is established in a concentrated manner below the electrodes. Since waveguides 2 and 3 are preset in the region having the electric field concentrated, there is established a phase difference DELTAbetaE between the waveguides. At an optical modulator 6, on the other hand, a thin film 14 for phase misalignment is mounted only on one waveguide 3. As a result, the coefficient of transmission of the waveguide 3 has been varied more than that of the waveguide 2 to that the phase difference DELTAbetaL inbetween can be made sufficiently larger than the coupling coefficient K of the intrinsic type between the two waveguides. As a result, no shift of optical waves takes place upon the phase misalignment. As a result, after the DELTAbetaL takes a preset value by the charge of the thin film 14, the intensity of the waveguides 2 and 3 at their emanating ends can be varied from 0 to 1 by varying the value DELTAbetaE within a range of ¦DELTAbetaE¦<pi. |
