Impact of ZnSe grain boundary density on few-cycle laser-resistance

Chemical vapor deposited (CVD) Zinc Selenide (ZnSe) window are often used in the high power laser system because of their extremely low (near-/far-)infrared absorption, and large transmission range (0.5um-22um). A good CVD process enables us to achieve the extreme purity needed for high-powered optics: 99.999% purity. Zinc vapor and H2Se gas react to form sheets of ZnSe on graphite susceptors. Different grain-sized polycrystalline ZnSe plates are precisely prepared and tooled to form optical windows or optical gain media. In recent years, in the area of few-cycle laser interaction with optic components, many new phenomena were found and investigated. Electron dynamic calculations were clearer and richer in this time domain[1-2]. Due to the potential applications in NIR few-cycle laser or attosecond laser generation, the single shot and multi-shot laser-induced damage threshold are tested in a multiplate supercontinuum-based few-cycle laser platform (12fs 1030nm centered) in CREOL according to ISO 21254. The damage threshold of different pulse numbers was carefully extracted. Laser-induced damage evolution along with the pulse number and grain boundary density are carefully characterized by SEM, AFM, and confocal Raman spectroscopy. Our experimental results will show the impact of grain boundary density on the laser-induced damage threshold of polycrystalline materials, which is of great value for future ultrashort laser pulse applications.