A Low-Wavelength Host Absorption Edge of Cesium-Lithium Borate CsLiB-=SUB=-6-=/SUB=-O-=SUB=-10-=/SUB=-

Abstract

We have carried out an experimental study of the VUV edge of the optical host absorption of cesium-lithium borate crystals CsLiB6O10 (CLBO). The transmission (T=293 K) and absorption (T = 80, 293 K) spectra were studied, the short-wavelength edge of the transparency band (cutoff wavelength) and the energy position of the edge fundamental absorption at which the absorption coefficient k=50 cm-1 were determined. The absorption edge temperature shift coefficient -5.5·10-4 eV/K was determined. Based on low-temperature reflection spectra (T=10 K, theta=17o, E=7-30 eV) the Kramers-Kronig method was used to calculate the spectra of optical constants: refractive index (n) and absorption index (k), real (ε1) and imaginary (ε2) parts of the complex permittivity , as well as the absorption coefficient μ. The lowest energy peak, due to electronic transitions from the top of the valence band to the states of the bottom of the conduction band, was studied in the ε2(E) spectrum, the thresholds for interband transitions were determined Eg=7.95 eV. The origin of the fundamental absorption edge of cesium-lithium borate is discussed. Keywords:: Cesium-lithium borate CsLiB6O10 (CLBO), host absorption edge, optical properties.