Microwave and magnetooptic measurements of nonlinear dispersive magnetostatic waves in a yttrium-iron-garnet-gadolinium-gallium-garnet waveguide

Abstract

Nonlinear propagation characteristics of magnetostatic surface waves (MSSWs) with carrier frequencies ranging from 0.5 to 7.0 GHz and magnetostatic forward volume waves (MSFVWs) with carrier frequencies ranging from 0.5 to 5.0 GHz in yttrium iron garnet-gadolinium gallium garnet waveguides have been measured in a delay line configuration using both microwave and guided-wave magnetooptic (MO) methods. The latter, involving noncollinear guided-wave MO Bragg interaction, was employed for the first time. For the MSSW, nonlinear characteristics including power limiting, discrete sideband modulation, continuum sideband modulation, and group splitting were observed and measured. Among such nonlinear characteristics, continuum modulation spectrum was observed and measured for the first time. For the MSFVW, nonlinear characteristics including parametric instability and soliton formation were also observed and measured. The MO data obtained by scanning the location of the incident light beam right beneath the input transducer and along the MSW propagation path has shown that the nonlinear characteristics observed were related to propagation and not to electromagnetic to MSW conversion effects at the input. Theoretical estimates are in a fair agreement with the experimental data. Finally, compression of an input pulse of 60 rf cycles (20 ns in width) to an output pulse of 6 rf cycles (2 ns in width) using a 3 GHz MSFVW pulse was also demonstrated.