Time-domain Electric Field Analysis of Few-Cycle Pulse Damage Behavior in Ultra-Broadband Chirped Mirrors

The laser-induced damage resistance performance of ultra-broadband chirped mirrors (UBCM) is a critical factor influencing the generation of petawatt or exawatt laser pulses in thin film compression techniques. In this study, a few-cycle pulse damage testing platform was set up, and two UBCMs with different designs were fabricated for a comparative study of their laser-induced damage. Because light of varying wavelengths forms an electric field at different times within UBCMs under few-cycle pulse irradiation, a time-domain electric field model was developed to obtain transient electric field variations and explain the damage behavior. The model successfully elucidated the origin of the damage and discrepancy between the two UBCMs in terms of damage thresholds, showcasing its potential applications in designing high-threshold UBCMs for high-power laser systems.