Reduction of the temperature dependence of the nonreciprocal effect of magneto-optic channel waveguides

The nonreciprocal effect is the difference Δβ = βforward - βbackward between forward and backward-propagation constants of optical modes. This effect is analyzed for the fundamental TM00 mode of channel waveguides in epitaxially grown magnetic garnet films. To increase |Δβ|, double layers with opposite signs of Faraday rotation are used to prepare the waveguides. It is shown that the temperature dependence of Δβ can be reduced considerably if the layer with positive Faraday rotation, which is at room temperature close to the Curie point, is replaced by a paramagnetic layer with negligible Faraday rotation. Concurrently, however, |Δβ| is decreased by ∼35% at 295 K.