Optical properties of lead germanate Pb5Ge3On in terahertz range

Abstract

We measured ordinary and extraordinary refractive index and absorption of ferroelectric lead germanate in the range of 0.1 - 1.3 THz by the method of terahertz time- domain spectroscopy. We studied soft mode behaviour with the rise of temperature by fitting imaginary part of the complex dielectric permittivity with three Lorentz oscillators. We found that high birefringence and dichroism of lead germanate or its analogues can be used for manufacturing of effective terahertz polarizing filters.