Investigation of parameters governing damage resistance of nematic liquid crystals for high-power or peak-intensity laser applications

We investigate the damage resistance of saturated and unsaturated liquid crystals (LC’s) under a wide range of laser excitation conditions, including 1053-nm pulse durations between 600 fs and 1.5 ns and nanosecond pulse excitation at 351 nm and 532 nm. This study explores the relationship between the LC’s resistance to laser-induced breakdown (damage) and the electronic structure (π-electron delocalization) of the constituent molecules. The laser-induced damage threshold at all wavelengths and pulse durations was consistently higher in saturated materials than in their unsaturated counterparts. The wavelength’s dependence in the results suggests that the energy coupling process that leads to laser-induced breakdown is governed by the energy separation between the ground state and the first and second excited states, while the pulse duration’s dependence in the results reveals the important role of electron relaxation between the excited states. A qualitative description was developed to interpret the experimental observations.