Section: Application Domains

Ultrashort Laser Pulses Propagation

One of the challenges in modern laser design is the improvement of the generation and manipulation of ultrashort pulses. These pulses are characterized by a short impulsion that typically lasts several femtoseconds. Recent innovations in ultrashort laser pulses open a wide range of possibilities in the interaction with matter and of applications. This scientific challenge is consequent, and has numerous applications : athermic micro-machining, imaging, optical surgery, meteorology, fundamental research .... For instance, the european project ELI (Extreme Light Infrasctucture) aims at reaching tremendous peak powers of about 200 PW for fundamental physical experiments. Nowadays, numerical simulations can help to better understand physics by solving more and more elaborated models, simulate more and more realistic phenomena. They also provide an efficient and attractive tool for designing since they are less expensive than physical experiments. A laser chain consists of a set of optical components (e.g. lenses, optical amplifier, mirror, crystal, ...), which have various effects on the impulsion. An exact solution can be obtained by solving non-linear Maxwell's equations, but a direct numerical simulation is too costly because the computational domain may comprise from a thousand wavelengths until several millions of wavelengths in the direction of propagation. Current numerical tools are based on the resolution of non-linear Schrödinger models, where dispersive and non-linear effects (Kerr effect, Raman effect, N-wave mixing, ...) are mixed. Those models are becoming less and less accurate with modern pulses because the bandwidth becomes larger and because the intensity becomes higher. In the future, more robust models and numerical tools will be needed.