Magneto-optical rotation of a one-dimensional all-garnet photonic crystal in transmission and reflection

摘要

We present spectra of transmittance, reflectance, and Faraday rotation of transmitted and reflected light for a periodic garnet multilayer structure with a central defect layer. The multilayer consists of alternating layers of bismuth and yttrium iron garnet, is 1.5 μm thick, and was prepared by pulsed laser deposition. For the reflection measurements, a silver mirror was evaporated on top of the multilayer. Faraday rotation is strongly enhanced at resonances in transmission and reflection. The peak value obtained at 748 nm in transmission is 5.3° and at 733 nm in reflection is 18°. A single layer BIG film of equivalent thickness shows 2.2° Faraday rotation at 748 nm. We find rather good agreement between measured and calculated spectra. Using calculations of the distributions of light intensities at different wavelengths inside the multilayer, we are able to give consistent qualitative explanations for the enhancement of Faraday rotation. We also find numerically that-at moderate strengths of the optical resonances-a linear relation exists between Faraday rotation and the intensity integrated over all magneto-optically active layers, if absorption is neglected.