Applications of magnetic garnet films in integrated optics

A novel type of optical waveguide isolator is proposed. It relies only on the TM₀ mode propagating in a strip waveguide which is divided by a compensation wall. The intensity distribution is different for forward and backward propagation. The backward mode can thus be eliminated by localized optical absorption. Detailed calculations exhibit the required geometry and material parameters. Furthermore, it is demonstrated that optical modulators can be realized using dynamical mode conversion introduced by ferrimagnetic, domain, and domain lattice resonances. Dynamical conversion efficiencies of 10% at frequencies up to 3 GHz are measured. The additional optical absorption caused by impurities incorporated into the garnet films during the epitaxial growth process can be reduced considerably by controlling the growth parameters, or by annealing treatments. Absorption constants of 0.2 cm^-1 at 1.3 μm wavelength have been achieved