Femtosecond laser damage resistance of beam dump materials for high-peak power laser systems

Ultrahigh peak power laser systems require highly absorptive and high-damage threshold beam dumps, which allow safe and reliable termination of the beam path in vacuum. We present promising optical materials for high-power laser beam dump designs. In order to evaluate the optimal beam dump performance of the various materials, we characterized the optical properties of these materials and measured their damage thresholds. The tested beam dump materials include highly absorptive (>99.8%) Vantablack coatings and absorptive glasses with different optical densities. The laser-induced damage threshold (LIDT) tests were performed using 800-nm ultrafast laser beams with a pulse duration of 40 fs at a 1-kHz repetition rate. The LIDT test methods, such as S-on-1 and R-on-1, were used for determining the damage threshold. The Vantablack coatings showed a moderate ultrafast damage threshold while being highly absorptive and applicable on metallic substrates. The absorptive glasses with high optical density have higher damage resistance and can be used for low-repetition rate applications with the highest intensities. By comparing the optical properties and LIDT results, we discuss the suitability of these beam dump materials for ultrafast high-power laser systems. (C) 2020 Society of Photo-Optical Instrumentation Engineers (SPIE)