Gyrotropic band gap optical sensors

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Faraday-effect-active photonic band gap structures fabricated in iron garnet films are shown to provide a platform for optical sensing based on refractive index detection. Strong near-band gap-edge polarization rotations serve as a sensitive probe to cover-index changes in birefringent magneto-optic waveguides. A wide index range from air to n=1.6 is explored. Device sensitivity is found to improve with cover index increase. Theoretical analysis of Bloch modes polarization state shows large near stop-band edge rotations and strong sensitivity to cover index. The combined effects of geometrical waveguide birefringence and Faraday rotation contribute to the strength of the sensor response. © 2010 American Institute of Physics.

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Applied Physics Letters