Structure analysis of terbium aluminosilicate glass
- PDF / 375,256 Bytes
- 7 Pages / 612 x 792 pts (letter) Page_size
- 36 Downloads / 211 Views
L6.18.1
Structure analysis of terbium aluminosilicate glass Xiaoyuan Qi, Sang-Yeob Sung, Samir K. Mondal and Bethanie J. H Stadler Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455, USA Glasses rich in rare-earth ions have attracted a lot of interest due to their applications in optical isolators and optical amplifiers. Integrating optical isolators with various optoelectronic devices allows sources to be integrated with lower costs, easier alignment and longer lifetimes. Glasses rich in rare-earth ions have large Verdet constants, so large Faraday rotations. Among the rareearth ions used in paramagnetic glasses, Tb3+ ions have largest Faraday rotation per ion and the glasses are transparent down to 1.6um. These glasses can also avoid the temperature incompatibility and lattice match problems which are encountered when magneto-optical garnets are used for integration. The Tb3+ doping is also widely used in optical amplifiers. In this paper we have explored the metastable phases present in the sputtered Tb-Al-Si-O system in order to fabricate paramagnetic films with the highest possible Faraday rotations, lowest optical losses and that are easily integrated with semiconductors. A broad peak was observed in the microdiffraction pattern around 2θ = 30deg. This peak corresponded with the close-packed Tb-O plane spacing (111 for FCC Tb4O7 or 002 for HCP Tb2O3), but it was an “amorphous” peak with a 5 deg FWHM. Amorphous films were obtained even when the Tb concentrations were very high. Since high concentrations of Tb are known to devitrify glasses, the discovery of a high-Tb concentrated glass is exciting.
I. INTRODUCTION Glasses rich in rare-earth ions have been widely used in optical isolator applications. In recent years, integrated optical isolators have attracted a lot of interests due to their low cost, convenience and long lifetimes. They are crucial parts of optical fiber communication systems and photonic integrated circuits. Isolators using Faraday rotation have been widely used in both bulk and thin film forms. Faraday rotation is a nonreciprocal effect. In the isolator application, the light is rotated about 45 degrees when it passes through the Faraday rotator in the forward direction and another 45 degrees when it is reflected in the backward direction. A polarizer is put in front of the Faraday rotator, and this will only allow the forward-traveling light to propagate. The backward-traveling light is blocked as it is 90 degrees to the polarizer, and in such a way, the laser or other light source is isolated from back reflections.
L6.18.2
Yttrium iron garnets (YIG) and substituted iron garnets, e.g. bismuth-substituted YIG (BiYIG), are mainly used for Faraday rotator applications. Liquid phase epitaxy (LPE) is usually used to grow these garnets. But the high temperature and epitaxial requirements are not compatible with semiconductors or other common substrates. Many efforts have been made to overcome these problems [1]-[6]. The replacement of garnets wi
Data Loading...
