Magneto-optic magnetic field sensors based on uniaxial iron garnet films in optical waveguide geometry

Iron garnet films which exhibit perpendicular uniaxial magnetic anisotropy are promising materials for magnetooptic magnetic field sensing. In an optical waveguide geometry, these materials exhibit large values of saturation Faraday rotation which in turn produce high sensitivity. The domain structure of these films favors magnetization rotation as the primary magnetization process. This process is significantly faster than domain wall motion, which is the primary magnetization process in bulk iron garnet crystals. Data which confirm the high sensitivity and wideband frequency response of these materials are presented. One film exhibits a virtually flat frequency response from DC to at least 1 GHz. Potential problems with waveguide sensors, such as birefringence and optical coupling efficiency appear to be soluble