Single-pulse and multi-pulse femtosecond laser damage of optical single films

Laser-induced damage of a single 500 nm HfO2 film and a single 500 nm ZrO2 film were studied with single- and multi-pulse femtosecond laser. The laser-induced damage thresholds (LIDT) of both samples by the 1-on-1 method and the 1 000-on -1 method were reported. It was discovered that the LIDT of the HfO2 single film was higher than that of the ZrO2 single film by both test methods, which was explained by simple Keldysh' s multiphoton ionization theory. The LIDT of multi-pulse was lower than that of single-pulse for both samples as a result of accumulative effect.