Far-infrared spectroscopy of terbium-scandium-aluminium garnet and terbium-scandium perovskite

摘要

Single crystals of the terbium-scandium-aluminium garnet (Tb_3Sc_2Al_3O_[12]) and terbium-scandium perovskite (TbScO_3) prepared using the micro-pulling down method represent important materials with potential in pho-tonics and optics. A method for far- and mid-infrared spectroscopy of the samples as small as 1 mm is proposed and tested in reflection and transmission configuration. High signal-to-noise ratio and high precision are obtained using the vacuum Fourier transform infrared (FTIR) spectrometer and a special pinhole holder. Reflectance spec-tra of the materials are measured in the spectral range from 7500 to 100 cm～(-1) (1.3μm - 100μm) for the angle of incidence of 11 degree. Optical functions were obtained by fitting of the data with the model dielectric function consisting of Lorentz damped harmonic oscillators and fulfilling the Kramers-Kronig dispersion relations.