Photonic bandgaps with defects and the enhancement of Faraday rotation

We investigate enhancement of magnetooptical rotation in periodic magnetic garnet thin-film stacks with defects using a combination of coupled-mode theory and matrix calculations. We prove that a combination of high rotation per unit length and high output is unattainable for a symmetric grating with a single central defect. We demonstrate that the addition of a second defect introduces sufficient degrees of freedom to allow high transmission for a much larger range of rotation angles than was previously possible. We present a number of designs with emphasis on achieving 45° rotation in very short propagation lengths.