High frequency light modulation by excitations of domain lattices in magnetic garnet films

Magnetic garnet films are grown by liquid phase epitaxy which support lattices of parallel stripe domains. The domain resonance and the domain wall resonance are excited at GHz frequencies using rf magnetic fields of proper polarization. The excited lattice acts as dynamic phase grating and can thus be applied for modulation of light. Two geometries are studied: (i) Optical modes propagate in the waveguiding film, modulation is achieved by dynamic mode conversion. (ii) Light passes the film perpendicular to the film plane and is modulated by diffraction. The modulation efficiencies are measured as function of the static induction applied in the film plane parallel to the stripe domains. From the experimental data the precession angles and the wall oscillation amplitudes are derived. The possibility of dynamic deflection of optical modes is discussed