| 摘要 |
<p>A waveguide-type optical circuit element which is equipped with a directional coupler that varies the intensity of light between two waveguides, and is used as a polarization-independent optical switch or a variable light-branching filter for optical fiber communication, etc. The length of the coupling portion of two waveguides (2) and (3) is, in the case of the TE mode, about three times as long as the complete coupling length of the TE mode. In the case of the TM mode, the length is nearly equal to the complete coupling length of the TM mode. Electrodes (4) and (5) each divided into three parts are inverted-Δβ electrodes in which the direction of the electric field is inverted alternately. Thus, the effect of confining the light in the waveguides is enhanced, and the driving voltage for optical switching is low. Optimum element characteristics are obtained according to the ratio of variations of the propagation constants of the TE and TM modes of the directional coupler fabricated.</p> |
