Wave-Front Correction of Femtosecond TeraWatt Laser Using a Deformable Mirrors

Abstract

Chirped Pulse Amplification (CPA) allowed the development of ultrashort, high intensity lasers. For many applications, laser users are interested in reaching the highest intensity focused on target. Often neglected, the spatial quality of the beam is crucial in this regard(1). Wave-front distortions can significantly affect this spatial quality and thus severely reducing the attainable focused intensity. In fact, the wave-front of multi-Terawatt lasers, because of thermal effects and the size of optical elements, features sizeable distortions. The correction of the wave-front and a better confinement of the energy is thus a solution much less expensive than adding one more amplifier stage to the laser chain to actually obtain the same peak intensity. To quantify this decrease in the peak focused intensity, we use the normalized Strehl intensity which is the ratio of the peak intensity at focus of a beam with a distorted wave-front to that of the same beam without distortions. We present, in this paper, the wave-front correction of a femtosecond TeraWatt CPA lasers using an Achromatic Three-Wave Lateral Shearing Interferometer (ATWLSI)(2) and a deformable mirror.