Shack-Hartmann Thermal Lensing Characterization of Mid-IR Materials

High brightness mid-IR sources have matured and are becoming viable solutions to many medical, defense, and sensing demands. Recently, super-continuum from 3.6-4.8μm with an average power of 22W has been demonstrated using a ZGP optical parametric oscillator [1]. To fully utilize the power and bandwidth of sources like these, passive optical components possessing both high optical and high thermal power handling capabilities are necessary. Glasses based on the chalcogenide elements show promise for these applications as they offer a large wavelength transmission window that spans from ~1μm to ~10μm [2]. However, many of these glass compositions require thorough evaluation of their thermo-optic behavior relating to both intrinsic properties and purity concerns. In order to evaluate the relative strengths of the thermo-optic responses of chalcogenide glasses, we utilize a CW pump-probe experiment in which the thermally induced parabolic phase is directly measured with a Shack-Hartmann array.