K4GeP4Se12: a case for phase-change nonlinear optical chalcogenide

Abstract

We report on broadband nonlinear optical (NLO) responses from a phase-change chalcogenide compound K4GeP4Se12. Its glassy phase exhibits unusual second-harmonic generation (SHG) due to the preservation of local crystallographic order. The SHG efficiency of the glassy form can be boosted by more than 2 orders of magnitude by simple heat treatment. Strong SHG and third-harmonic generation from both glassy and crystalline compounds were characterized over a wide wavelength range of 1.2-4.0 mu m. Our results imply that K4GeP4Se12 can be utilized for various NLO applications in the mid-infrared spectrum. (C) 2013 Optical Society of America