Broadband high-reflectivity dispersive mirror in a 100-PW laser system

In 100-PW laser systems, the reflective components used for transmitting nanosecond pulses must operate over a bandwidth exceeding 200 nm while maintaining an extremely high laser-damage threshold, which has long posed a critical challenge in optical coating design. This study proposes a novel solution for designing and fabricating 250-nm broadband high-reflectivity dispersive mirrors with controllable flat dispersion and a high damage threshold for use in 45° p-polarization employing a floating dispersion-flattening design method, to meet the requirements for transmitting ultrabroadband, high-energy nanosecond pulses in 100-PW systems. The damage threshold of the designed broadband high-reflectivity dispersive mirror was systematically measured using 3-ns pulses in the spectral range of 800–1050 nm. The damage morphology was observed, and the damage mechanism was analyzed by simulating multi-wavelength electric and thermal-stress fields. This study presents new perspectives for advancing the operational bandwidth and laser damage resistance of broadband, high-energy nanosecond pulse transmission optics in 100-PW laser systems.