Femtosecond laser processing of materials

Chemical bonding, phase transitions, and surface processes occur on timescales comparable to the natural oscillation periods of atoms and molecules, in the range of femtoseconds (1 fs =10–15 s) to picoseconds (1 ps = 10–12 s). Advances in the generation of ultrashort laser pulses in the past two decades have made it possible to directly observe these fundamental processes. These advances have taken us from the picosecond timescale a generation ago, to the femtosecond timescale in the past decade, and recently into the attosecond (1 as = 10–18 s) regime. Materials science, interdisciplinary by nature, has benefited from these advances because recent studies, ranging from probing atomistic processes in model materials, to real-time diffraction of lattices and to ultrafast laser processing of materials are furthering our understanding of time-dependent processes in materials. [1] In this tutorial presentation, I will review recent work involving the interaction of femtosecond laser pulses with materials. I will discuss the fundamental processes involved and a number of applications, classifying the work into two parts: the interaction with transparent materials (bulk femtosecond micromachining) and interaction with absorbing materials (femtosecond surface structuring and hyperdoping).