Mode conversion induced by magnetostatic surface waves (MSSW) has a great potential for a variety of optical signal processing devices. However, till now, analysis of optical-MSSW interaction has been limited planar waveguides. We investigate into the mode conversion induced by MSSW in three-dimensional optical waveguides. In this paper, at first, the problem faced in propagating MSSW in three-dimensional waveguides is discussed and a device configuration is presented to overcome the problem. Next, an analysis of the MSSW induced optical mode conversion in the proposed configuration is given. The coupling coefficient between the Ezpq and the Expq modes of the waveguide is derived and its variation with the waveguide dimensions is discussed. Finally, the feasibility of the proposed configuration is demonstrated by a numerical example.

Optical-MSSW interaction has received wide interest for realization of thin film devices for optical signal processing at microwave signal frequency. In this paper, a device structure to obtain optical-MSSW interaction in a three-dimensional optical waveguide using a multilayered garnet structure is proposed and analyzed. The multilayered structure enables optimization of the waveguide parameters, separately, for optical and MSSW propagation. Interaction in a three-dimensional optical waveguide is promising for integration of the device with other optical integrated circuits. Optical and MSSW propagation characteristics in the multilayered device are investigated and the optical mode conversion characteristics between the Ezpq and the Expq modes supported by the three-dimensional optical waveguide are derived. The dependence of the mode coupling coefficient on the waveguide parameters, such as the film thicknesses, waveguide width, saturation magnetization, and the MSSW power is also analyzed. It is demonstrated through a numerical example that, by proper selection of the waveguide parameters, it is possible to achieve practical device dimensions.