Noah Talisa’s (from Chowdhury group) oral presentation titled, “Single-shot femtosecond laser-induced damage and ablation of HfO2/SiO2-based optical thin films: a comparison between few-cycle pulses and 110 fs pulses” at the 2019 SPIE Laser Damage Conference in Boulder, CO has been selected for the MJ Soileau Best Student Paper Award.

Noah used light pulses that are approximately 3 optical cycles long (8 femtoseconds), to damage and ablate sub-micron thick oxide layers (SiO2 & HfO2 based interference coatings), and follow their temporal evolution to almost seven orders of magnitude in time, up to 45 nanoseconds after the single pulse initially is incident on the sample surface. His results show many stages of non-perturbative interactions, first, electron-hole plasma creation in thin dielectric films, then recombination over a few picoseconds, and material modification beginning around 50 ps, material layer expansion until ~5 ns, and then fracturing and breakup of layers tracked up to 45 ns.

Noah is preparing several manuscripts based on his work. His work illuminates how few cycle pulses (FCP) interact differently with solids than longer pulses in this non-perturbative regime, and will pave the way for development of more damage resistant ultrabroadband optics. A related paper was published before [N. Talisa and E. A. Chowdhury, "Few cycle pulse laser ablation study of single layer TiO2 thin films using time resolved surface microscopy," Opt. Express 26(23), 30371–30382 (2018).].