Generation of 50 TW subpicosecond pulses in a Nd-Glass Chain and focusability study

Abstract

There has been recently a great deal of works on the development of ultrabright sources in order to study the interaction of matter with such intense pulses. A very interesting goal is to obtain intensities above 1019 W/cm2 because new effects are expected in this regime such as relativistic electrons, coherent X-Ray short pulses, huge shock pressures in dense and hot plasmas,... Solid state broadband amplifying media coupled to the Chirped Pulse Amplification technique [1] is the most direct way to get intense and ultrashort pulses. Ti-Sapphire, Cr3+:LiCAF, Alexandrite are such good media. Nd-Glass has the potential to amplify pulses only longer than 250 fs but because of the available amplifiers size allows very energetic pulses up to kilojoules. In a first experiment we started from a CW-Mode-Locked-Nd-YAG oscillator coupled to a fiber, injected into a Nd-Glass regenerative amplifier and in a Nd-Glass power chain. The 60 J chirped pulses were then compressed using double pass compressing scheme. 20 TW-24J and 1.2 ps pulses are then delivered [2]. However the intensity contrast in this system is very poor. We have developed a new source based on a double fiber scheme [3] and a Ti:S amplifier allowing to get clean 450 fs pulses. The chirped pulse is sent in a regenerative amplifier able to increase the pulse energy from a few nJ to 1 mJ without gain narrowing for a 8 nm spectral bandwidth [Fig. 1, Fig. 2.]. These pulse is then sent into the Nd-Glass power chain and further compressed.