Abstract
The Faraday effect in ferrimagnetic garnets can be used as the basis for fiber optic magnetic field sensors [1,2]. Single crystals of substituted yttrium iron garnet (YIG) can be in bulk form, or epitaxial thin films with planar anisotropy [3], or thick films with uniaxial anisotropy perpendicular to the surface [4]. The growth of magnetic domains parallel to the applied field at the expense of antiparallel domains results in changing Faraday rotation of the plane of polarization of transmitted infrared light. In this paper we report on the sensitivity and speed of sensors based on thick uniaxial garnet films, with the applied field and the light propagation direction perpendicular to the film. In zero field, these films have up and down magnetic domains of equal area, forming the familiar stripe pattem shown by their Faraday rotation in Figure 1. The changes in this pattem with magnetic field determine the sensitivity and limit the maximum operating speed of a magnetic field sensor.
© 1992 Optical Society of America
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