Femtosecond laser-induced damage threshold of nematic liquid crystals at 1030  nm

Abstract

The laser-induced damage threshold (LIDT) of nematic liquid crystals is investigated in the femtosecond regime at 1030 nm. The thickness and breakdown of freely-suspended thin films ( 100 nm) of different mixtures (MLC2073, MLC2132 and E7) is monitored in real time by spectraldomain interferometry. The duration of laser pulses was varied from 180 fs to 1.8 ps for repetition rates ranging from single-shot to 1 MHz. The dependence of the LIDT with pulse duration suggests a damage mechanism dominated by ionization mechanisms at low repetition rate and by linear absorption at high repetition rate. In the single-shot regime, LIDTs exceeding 1 J/cm 2 are found for the three investigated mixtures. The LIDT of polyvinyl alcohol (PVA) is also investigated by the same method.