Temperature-wavelength dependence of terbium gallium garnet ceramics Verdet constant

Abstract

A polarization-stepping method for measurement of the Faraday rotation in magneto-active materials has been modified for evaluating the Verdet constant as a function of wavelength and temperature. It has been used for a comparison of wavelength and temperature dependent Verdet constant, dominant electronic transition wavelength, and Curie-Weiss temperature in terbium gallium garnet (TGG) single crystals and TGG ceramics samples. The room-temperature values of Verdet constant varied from 36.6 to 44.2 rad/T.m at 1.064 μm wavelength and from 122.4 to 155.5 rad/T.m at 0.632 μm wavelength for all samples under investigation. These results match very well the values obtained from single wavelength measurement in the literature and show the same measurement error for single crystal and ceramics, respectively. The Curie-Weiss temperature has been evaluated for the first time in TGG ceramics. This method could be used for the detailed characterization of magneto-optical properties of the materials over a wide range of wavelengths and temperatures which is of great importance for the proper design of Faraday devices.