Damage threshold of poly(methyl methacrylate) (PMMA) nanostructures at MIR resonant frequencies

This study examines the damage threshold of poly(methyl methacrylate) (PMMA) nanostructures when exposed to high-intensity mid-infrared (MIR) light. U-shaped PMMA nanostructures were arranged on a CaF₂ substrate, with resonant frequencies identified between 1724–1730 cm^-1 using FTIR and AFM-IR, corresponding to the carbonyl (C=O) stretching vibration. A femtosecond laser at a 10 kHz repetition rate delivered 180 fs pulses with 9 µJ per pulse and a 100-micron spot size, resulting in rapid damage to the nanostructures. Findings suggest that both resonant absorption and cumulative thermal effects contributed to damage. Future work will explore single-shot pulses and varying intensities to better understand the interplay of resonant absorption and thermal damage, aiding the development of advanced materials for high-intensity MIR applications.