Abstract

Noncollinear magnetooptic (MO) Bragg interactions between guided-optical waves and magnetostatic waves (MSWs) in Yttrium Iron Gamet-Gadolinium Gallim Garnet (YIG-GGG) waveguides¹ have resulted in guided-wave MO Bragg cells in analogy with guided-wave acoustooptic (AO) Bragg cells.² Figure 1 shows the interaction geometries depicting the distinct directions of the DC magnetic filed (Ho) for the three cases that involve, respectively, the three distinct types of the MSWs. Propagation of the MSW generated by the input microstrip transducer induces moving optical diffraction gratings in the YIG-GGG waveguide through the Faraday and Cotton-Mouton effects.¹ Portions of the input guided-light wave, incident upon the resulting gratings at Bragg angle, is diffracted and frequency-shifted, and propagates at the Bragg angle with respect to the gratings in the plane of the waveguide. The intensity of the Bragg-diffracted light is directly proportional to the power of the MSW before saturation sets in. The diffracted light is scanned in the plane of the waveguide as the carrier frequency of the MSW is varied. In contrast to guided-wave isotropic AO Bragg diffraction, the output angle of the diffracted light does not vary linearly with the carrier frequency of the MSW as a result of the dispersive property of the MSW. Also, for the same reason the diffracted light is also scanned in the plane of the waveguide as the DC magnetic field is varied, while the carrier frequency of the MSW remains fixed. In analogy with the AO Bragg cells,² the resulting devices are called the MO Bragg cells.³

© 1995 IEEE