New garnet films for magneto-optical photonic crystals

Epitaxial La3Ga5O12 (LGG) garnet films and Bi3Fe5O12/La3Ga5O12 (BIG/LGG) heteroepitaxial structures have been synthesized on Gd3Ga5O12(GGG,111) single crystal. LGG films were grown by Pulsed Laser Deposition (PLD) technique whereas rf-magnetron sputtering was used to grow BIG films. We demonstrate LGG is a promising material to be integrated with a giant Faraday rotator Bi3Fe5O12 in magneto-optical photonic crystals. LGG has a lattice constant 12.772 angstrom that is bigger than that in GGG (12.384 angstrom) and closer to that in BIG (12.626 angstrom). Heteroepitaxial Bi3Fe5O12(2 mu m)/La3Ga5O12(300nm) structures grown on the GGG(111) single crystal show the Faraday rotation as high as 5.74 deg/mu m compared to 5.46 deg/mu m in BIG/GGG at lambda = 655 nm. Fitting LGG reflectivity spectra to Fresnel formulas yields LGG refractive index n = 1.981 compared to 1.963 in GGG at 655 nm. Dispersion of LGG refraction index follows Sellmeier formula n(2) = 1 + 2.78/[1 - (138nm/lambda)(2)] in the range from 400 nm to 1000 nm.