Kunihiro Naoe

Faraday rotator properties of {Tb3}[Sc1.95Lu0.05](Al3)O12, a highly transparent terbium-garnet for visible-infrared optical isolators

The optical and magneto-optical properties of the {Tb3}[Sc1.95Lu0.05](Al3)O12 garnet (TSLAG) crystal are analyzed in detailed and compared with those of the reference compound Tb3Ga5O12 (TGG). TSLAG presents a very high transmittance, particularly higher than that of TGG in the visible region, and its Verdet constant is 20% larger at any wavelength. The figure of merit and extinction features point out the superior characteristics of TSLAG respect to TGG. A prototype, polarization independent optical isolator based on a TSLAG rotator is demonstrated at 1080 nm. Its performance confirms the high optical quality of this crystal, indicating its mature development for Faraday rotator applications.

AlN bulk single crystal growth on SiC and AlN substrates by sublimation method

Aluminum nitride (AlN) bulk single crystals up to 45 mm in diameter and 10 mm in thickness have been successfully grown on 6H-SiC(0001) substrates by the sublimation method. Moreover, high growth rate of 200μm/h has been achieved by high temperature homo-epitaxial AlN growth on AlN(0001) substrate. The Raman spectrum indicates that the polytype of the grown AlN single crystals is a Wurtzite-2H type structure, and the crystals do not include any impurity phases. In both the hetero- and homo-epitaxial AlN bulk single crystal growth, the quality at the top of the crystal improves as the crystal thickness increases along the <0001> direction during the growth: low etch pit density 7 × 104 cm−2 and 1 × 104 cm−2 have been achieved at a thickness of 8 mm and 2 mm in the hetero- and homo-epitaxial growth, respectively.