Characterization of Ferrimagnetic Garnets for MSW-Optical Diffraction

Bragg diffraction of guided optical waves by magnetostatic waves (MSWs) in thin film garnets will prospectively provide devices for signal processing at frequencies up to 20 GHz. Presently, advances in device performance are limited by low diffraction efficiency and by optical and MSW absorption. Use of improved garnet materials can circumvent these barriers. The materials properties required are: high Faraday rotation and low optical absorption and scattering, and low MSW absorption (i.e., low ferrimagnetic resonance linewidth). These garnet properties can be most critically influenced by substitutional constituents in the film composition. A coordinated effort for optimization of garnet materials for MSW and optical propagation and interaction has been pursued, employing measurement of ferrimagnetic resonance linewidth, saturation magnetization, Faraday rotation, and optical absorption.