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Microwaveguides for spin waves based on yttrium iron garnet films and cross-like structures built on such waveguides are experimentally studied. Additionally, effects of the waveguides geometry, location of the microantennas for excitation and detection of the spin waves, and geometry of the waveguides junctions on the spin wave excitation and propagation efficiency are discussed.
A simple thin film effective index analysis for first order gratings in Si photonic waveguides is shown to provide highly accurate results for reflected and transmitted power spectrums as long as the waveguide remains single mode and non-radiating. A cover layer can be added to the grating region of a Si photonic waveguide to increase the strength of the grating, modify transition losses from the input waveguide to the grating waveguide region, and/or modify the width of the reflectivity spectrum. For a given grating period, the peak reflection and spectral width of the reflectivity decrease as the duty cycle is decreased or increased from ~50%. For both radiating and multimode structures, the coupling between all modes, power radiated towards the superstrate (upwards), power radiated downwards (substrate) and transmitted power analyzed by Floquet-Bloch, Eigenmode Expansion and Finite Difference Time Domain methods show excellent agreement. Coupling coefficients calculated using analytic formulas are shown to be accurate only for shallow grating depths.