Semileaky‐type thin‐film magneto‐optic waveguide for modulator application

摘要

This paper is concerned with a light‐intensity modulator that utilizes codirectional magneto‐optic coupling between orthogonally polarized guided and radiation modes a thin‐film waveguide. The basic structure is the semileaky‐type anisotropic waveguide that has been previously used as the polarization mode filter. Specific features of the modulator of this type are (1) phase matching is automatically achieved without introducing an acoustic wave, a gratinglike periodicity, or a precise control of film thickness and (2) direct intensity modulation is possible with no separate analyzer or mode splitter. As a practical example, a modulator configuration using LiNbO3/YIG/GGG layered structure operating in 1.15‐μm wavelength region is considered. Radiation loss of 5–10 dB/cm may be obtainable in the film of thickness 6–7.5 μm for the lowest‐order guided mode.