Temperature oscillating optical second-harmonic generation in TlGaSe2 and TlInS2 single crystals

Abstract

Second-harmonic (SH) generation effects have been investigated in TlGaSe2 and TlInS2 layered crystals. Pronounced periodical changes of the SH signal with temperature are discovered. The observed effect is explained within the phase synchronism condition, which changes with temperature in the course of thermal expansion. A major role of the high value of dispersion for the refractive indexes of the investigated crystals in the observed phenomenon is proposed.