Third-harmonic generation measurement of nonlinear optical susceptibility χ^(3) of Ge-Ga-Sb-S chalcogenide glasses proposed for highly nonlinear photonic fibers

Abstract

We measured the nonlinear optical susceptibility χ(3) of some Ge-Ga-Sb-S chalcogenide glasses feasible for the fabrication of highly nonlinear photonic crystal fibers. The χ(3) values of Ge17Ga4Sb10S69, Ge20Ga5Sb10S65, and Ge20Ga5Sb6S69 glasses were found to be 3.5, 2.6, and 1.8×10−19m2/V2 (6.3, 4.6, and 3.2×10−12esu, where “esu” stands for electrostatic unit) at the fundamental wavelength λ=1.9μm, i.e., 227, 167, and 117 times higher than that of standard silica [1.55×10−21m2/V2 (2.79×10−14esu)]. Their nonlinear refractive indices n2 were then obtained as 1.8, 1.3, and 1×10−17m2/W (5.1, 3.7, and 2.7×10−11esu). They are ∼78, 56, and 43% of n2=2.3×10−17m2/W (7×10−11esu) of the As2S3 glass used as the chalcogenide glass reference.