A generalized rigorous Floquet scattering-matrix method for stratified anisotropic optical media, subject to a periodic spatiotemporal modulation, is formulated and implemented. The method is applied for studying an optomagnonic cavity formed by an in-plane magnetized ferrite film, in which a magnetostatic surface spin wave propagates, sandwiched between two nonmagnetic dielectric Bragg mirrors. Our results provide unambiguous evidence that externally incident light, when trapped in a cavity mode, experiences a strongly enhanced interaction with the spin wave due to the increased coupling time, which can give rise to pronounced effects if the appropriate selection rules are fulfilled. By means of systematic calculations we reveal and explain some remarkable features of this interaction, such as formation of spectral gaps, controllable transmission, and the emergence of inelastic diffracted beams, and show that efficient conversion of the optical wave can be achieved by triply resonant inelastic scattering through (multi)magnon absorption and emission processes.
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Department of Physics National and Kapodistrian University of Athens University Campus GR-157 84 Zografou, Athens
