The invention of Chirped Pulse Amplification (CPA) by Mourou and Strickland (2018 Nobel Prize in Physics) allowed the rapid development of high power ultrafast lasers that is opening up novel pathways in Material Science and Engineering. high intensity lasers are used as the finest ‘scalpels’ of the universe to perform eye and other surgeries 1,2, surface engineering 3,4 (e.g. super-hydrophobic surfaces) and machining 5 not possible before. At the heart of many of these phenomena is the femtosecond laser induced damage (fs-LID) of solids, during which, a strong, non- perturbative optical field near–instantaneously6 creates a high density of carriers (plasma) via electron transition from valence to conduction band (multiphoton to tunneling process, VB → CB), accelerates the carriers non-thermally, which, eventually thermalize within themselves and imparts energy to the lattice. Depending on how much energy density is transferred to the lattice in a pulse, the solid may exhibit rapid phase change and experience ablation, liquefaction, amorphization and disorder with corresponding change in surface morphology (damage but not ablation), or undergo changes to subtle to observe by traditional means (optical or electron microscopy of surface), but extremely important for understanding of multi-pulse effects. Although experimental, theoretical and computational efforts on this topic have been ongoing for over two decades, most of them were not coordinated to tackle a fundamental non-perturbative phenomenon whose temporal regime extends from attoseconds (ionization/transition) to nanoseconds (material removal) and beyond 7. Thus, significant gaps in fundamental understanding remain to this day. My lab investigates these processes by using dynamic and non-dynamic techniques, varying laser pulse durations (few to many cycles of optical oscillations) and wavelengths (near to mid-IR).
- Strong laser fields modify materials and material systems 8–10
- Material and material systems alter strong laser fields. 11–13
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