Measurement of magnetostatic wave profiles using the interaction with transverse optical guided waves

The profile of magnetostatic forward volume waves along the direction of propagation is measured using the transverse interaction with optical guided modes. The technique is used in regimes of both linear and nonlinear magnetostatic wave excitation. A microwave input power of up to 700 mW in the frequency range of 6-8 GHz was used to excite magnetostatic waves in a 6.3 μm film of (BiLu)₃Fe ₅O₁₂. The optical wavelength used in the experiment was 1.32 μm. At distances beyond about 1 min from the transducer, we observed an approximately exponential decay with a rate of about 40 dB/cm. The profile departs from an exponential shape at distances closer than 1 mm, owing, we believe, to transducer fringing field effects and the finite resolution of the probe beam. The nonlinear microwave frequency shift of the interaction spectrum was also observed at high magnetostatic wave power levels