Polarization-dependent, defect-driven damage in multilayer dielectric coatings under picosecond laser irradiation

MLD coatings located in the beam transport section of picosecond–petawatt-class laser systems were subjected to laser irradiation under varying polarization states. However, the effect of laser polarization on defect-driven damage mechanisms remains unclear.

This study investigated the role of polarization in the ps laser damage mechanisms of two typical types of defects in MLD coatings, namely nano-absorbing defects and nodular defects. Laser damage experiments were conducted on high-reflectivity HfO₂/SiO₂ coatings using 1053 nm, 8.6 ps laser pulses under both s- and p-polarization conditions. For damage pits induced by nano-absorbing defects, the laser-induced damage threshold (LIDT) was lower under p-polarization than s-polarization conditions.