Femtosecond laser-induced damage threshold of a thermo-optically addressed spatial light modulator due to giant third-harmonic generation

We investigate the resistance to the laser flux of a complex multilayer structure containing liquid crystal, focusing on the behavior of a spatial light modulator operating in the femtosecond regime. Our findings show that exceptionally high third-harmonic generation at the interfaces between the liquid crystal layer and its substrates, driven by the discontinuity in third-order nonlinear susceptibility, is the primary cause of laser damage. A quantitative study of the chromatic laser-induced damage threshold (LIDT) of a thermo-optically addressed spatial light modulator (TOA-SLM) is then presented. Since the device operates over an ultrabroadband spectrum, the study focuses on the behavior in the ultrashort pulse regime. The chromatic analysis offers a detailed map of the device's operational limits in ultrafast optics. With a maximum LIDT value of , the modulator is an excellent candidate for integration into ultrafast optical systems. Additionally, the study examines the laser-induced functional threshold (LIFT), showing that the device remains fully operational nearly up to its damage threshold.