Ultrafast nonlinear refraction measurements of infrared transmitting materials in the mid-wave infrared.

We utilize the conventional Z-scan technique to provide absolute measurements of third-order nonlinear refraction coefficients (n(2)) in the mid-wave infrared at 2 mu m and 3.9 mu m of common optical materials that have transparency windows spanning this regime. We study a variety of narrow band gap and wide band gap semiconductors, fluoride crystals (BaF2, CaF2, LiF, and MgF2) and optical glasses, and a series of chalcogenide glasses. The n(2) is found to span on the order of similar to 10(-15) to similar to 10(-12) cm(2)/W for the semiconductors, similar to 10(-16) cm(2)/W for the fluoride crystals and glasses, and similar to 10(-14) to similar to 10(-13) cm(2)/W for the chalcogenides. The experimental results are compared to previous measurements of n(2) conducted in the visible and near-infrared along with empirical and theoretical formulations. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement