ZnGa2Se4, a nonlinear material with wide mid infrared transparency and good thermomechanical properties

摘要： During the last decades, mid-infrared (3–12 μm) laser sources using crystals with nonlinear optical properties have attracted a particular attention due to their potential applications in different fields such as optical counter-measures and remote chemical sensing. As transparency of common oxide crystals is limited to about 4 μm, many researches have been focused on chalcopyrite compounds because of their wide transparency in the mid-IR range and their strong nonlinear optical coefficients. There is a need of such crystals able to convert efficiently the near infrared wavelengths from commercially available lasers into wavelengths higher than 5 μm through Optical Parametric Oscillators (OPO) systems. This paper presents a new compound: ZnGa2Se4 (ZGSe). Measurements made on dense polycrystals show a high thermal conductivity value in comparison with other selenides (2.9 W m?1 K?1), a wide transparency from visible to beyond the band III of the mid IR (0.6 μm–17 μm) and a coefficient of thermal expansion inferior to 10?5 K?1. These results are very encouraging and improvements of the growth process are now undertaken to obtain single crystals with the required optical quality.