MAGNETOOPTIC MAGNETIC-FIELD SENSORS BASED ON UNIAXIAL IRON-GARNET FILMS IN OPTICAL WAVE-GUIDE GEOMETRY

Iron garnet films which exhibit perpendicular uniaxial magnetic anisot ropy are promising materials for magneto-optic magnetic field sensing. In an optical waveguide geometry, these materials exhibit large value s of saturation Faraday rotation which in turn produce high sensitivit y. The domain structure of these films favors magnetization rotation a s the primary magnetization process. This process is significantly fas ter than domain wall motion, which is the primary magnetization proces s in bulk iron garnet crystals. We present data which confirm the high sensitivity and wideband frequency response of these materials. One f ilm exhibits a virtually flat frequency response from de to at least 1 GHz. Potential problems with waveguide sensors, such as birefringence and optical coupling efficiency, appear to be soluble.