Harmonic sources

Harmonics’ generations in solids or the heating of a solid target to obtain a very dense and hot plasma depends crucially on the lenght of electronic density gradient produced in front of the target before the pulse. This gradient is related to the presence of laser pulses arriving on the target before the main pulse. These pre-impulse are often deleterious.

A possible way to improve laser pulse is to use plasma mirror. The principle is simple, the laser beam is focused on a transparent dielectric. When the intensity is sufficient, the dielectric “slams” and becomes reflective. Of course, the contrast can be improved by using several mirrors.

One of the first applications with an improved laser impulse is to produce a large number of intense harmonics on a solid target. It is possible to obtain a gain of several orders of magnitude in flow compared to conventional XUV-harmonic’s sources in gases opening the non-linear domain largely to extreme ultraviolet. The production of attosecond laser pulses (10-18 second) at high intensities should allow significant advances in different emergent fields of physics.