Femtosecond lasers: Powerful tools for clean material processing

The advent of table top high repetition rate regeneratively amplified femtosecond lasers has opened the way to many recent and fast developments towards applications of economical interest. The most well known are microprocessing, thin film elaboration, waveguide photoinscription, surface treatment, dentistry, ophthalmology. Recent studies on microprocessing and laser-matter interaction using femtosecond lasers are reported. This is done using largely presently performed work in Saint-Etienne including investigations on Heat Affected Zone (HAZ), plume expansion characterization, and thin film elaboration. Indeed specific characters appear as compared to what is obtained using multipicosecond/nanosecond laser pulses: Typical submicronic HAZ lengths have been evidenced and particle energies of plasma plume ranging up to a few KeV (carbon target) using typical pulse energies of 1 MJ (150 fs, 800 run, 1 KHz), creating specific conditions for deposition. The concept of the often vocabled "athermal" interaction is discussed. Emphasis on actual microprocessing capability of the existing sources to approach industrial applications are questioned in terms of energy per pulse, timewidth, repetition rates and the need for further source development and control beam improvement stressed. A brief review of the progresses under way in these fields and their capability to answer to actual large scale commercial applications are given.