Optical TE-TM mode conversion in double epitaxial garnet waveguide

TE-TM mode conversion was examined in two-layer epitaxial garnet films, with (Sc, Ga) substituted YIG films on a GGG substrate. Mode conversion efficiency of 96% was observed in a single-mode waveguide over a 4.0-mm propagation distance at 1.15-microm wavelength. Mode conversion was increased by 2.0 X 10(-4) optical anisotropy arising from the photoelastic effect of a 0.03% lattice mismatch between the guiding layer and the substrate. A 45 degrees polarization rotator becomes possible because the TE and TM mode degeneracy is nearly complete. A novel waveguide optical isolator using the 45 degrees rotator is proposed.