Ultra high damage threshold optics for high power lasers

摘要

The output energies of lasers have increased year-by-year since their invention. Compared to this increase of laser energies, the damage threshold of optical components has not strongly changed. Therefore, the size of optics in high-energy laser system increases. This situation could change dramatically if optics with higher damage threshold were developed. Here, we propose a high damage threshold optics using a neutral gas as an active medium. More than 95% diffraction efficiency has been achieved. The damage threshold for a 6 ns laser pulse is measured to be 1.6 kJ/cm2. The aperture size of the present system is about 60 mm2. Based on this result, we anticipate that control of a 1 kJ laser beam may be achievable using 1 cm sized optics, driven by a  50 mJ ultraviolet laser, making this scheme promising in high power laser applications. In high-power lasers, beams are expanded to the order of meters such to avoid damaging optical element, but increasingly large optics are impractical. Here, a diffraction grating based on laser-induced density modulations of a gas is shown to exhibit an enhanced damage threshold for nanosecond pulses.