Fabrication and characterization of highly Dy3+- and Tb3+ -doped germano-borate glasses for magneto-optic device applications at 1.55 mu m

Abstract

Highly Dy3+- and Tb3+-doped germano-borate glasses with different rare-earth ion concentrations (10-25 mol %) were fabricated and their thermal, thermo-mechanical, optical, and magneto-optic (MO) properties were investigated with respect to the rare-earth ion concentration. The glasses showed high transmission properties of > 83% in the near-infrared regions of approximately 1.5 and 2.1 mu m. The MO properties of the glasses were investigated using Faraday rotation measurements at 1.5 mu m. The large Verdet constants of -5.35 and -6.11 rad/(T.m) at 1.55 mu m were obtained for the glasses incorporated with the highest Dy3+ and Tb3+ concentrations of 25 mol% and 16 mol%, respectively; this was due to large effective magnetic moments and electronic transition frequencies of the rare-earth ions. The results showed that the germano-borate glasses doped with high Dy3+ and Tb3+ concentrations are promising MO materials for application in MO devices in the near-infrared region.