Lectures About Intense Lasers: Amplification Process

Abstract

The laser lecture about intense lasers is dedicated to the basic process of stored energy and amplification and the way to achieve high intensity when considering the shortest possible pulse duration. The amplification course is essentially based on the semi-classical model that represents the interaction between electromagnetic radiation and an assembly of atoms. On the radiation side, we always start with Maxwell’s equations to arrive at the Helmholtz propagation equation, whereas on the atomic side the system will be represented by the two-level model. From there we can extend this model to the case of amplification, gain and stored energy. Many useful quantum aspects will be mixed with this model but we will always try to strive for the greatest possible simplification in order to have the most user-friendly formulas possible and especially not to lose the underlying physical reality. For accessing high peak powers, we will give a short description of the different techniques that were used since the very beginning of laser operation in 1960 and we will show that a major step was made in 1985 when the chirped pulse amplification process (CPA) was demonstrated. This year 2018 was somehow the celebration of this major event when the Nobel prize in Physics was delivered to Gérard Mourou and Donna Strickland.