Electronic spectral parameters and IR nonlinear optical features of novel Ag 0.5Pb 1.75GeS 4 crystal

Abstract

In this paper, we report on novel Ag0.5Pb1.75GeS4 single crystals grown by the Bridgman–Stockbarger method. For these crystals we have performed X-ray photoelectron spectroscopy (XPS) studies of the valence-band and core-level electron states. Second harmonic generation efficiency of Ag0.5Pb1.75GeS4 powder samples by using CO2 laser light depending on the power density up to 1100 MW/cm2 has been obtained within the temperature range 77–520 K. The obtained dependences indicate relatively strong enhancement of photoinduced SHG output efficiencies as temperature increases. Both the spectra taken at ambient and 520 K temperatures have shown similar behavior—rapid growth to saturated values of SHG efficiency with an increase of fundamental beam power density up to 400 MW/cm2, then slowly decreasing with power density reaching a value of 800 MW/cm2 and finally these features show a second small maximum at a fundamental beam power density equal to 900 MW/cm2. Beyond this power density both SHG values start to decrease