Abstract

The advent of the Chirped Pulse Amplification (CPA) [1] technique coupled to the development of solid state lasers capable to deliver ultrashort pulses in the tenth of femtosecond regime has opened the new experimental field of ultrahigh intensity physics [2]. New crystalline amplifying materials such as Ti-sapphire or Cr³⁺-doped LISAF or LICAF are central components of such setup able to deliver femtosecond pulses in the sub-joule regime [3]. However many of the envisioned applications, such as for instance the concept of achieving fast ignition of an inertially confined D-T capsule [4], rely both on the use of very large electromagnetic field amplitudes corresponding to intensities above 10¹⁹-10²⁰ W/cm², and on very high energy delivery. Such needed levels of energy, in the hundred of joules if not kilojoules range, cannot be obtained in small crystalline media or in gazeous media, but only in large volumes of solid materials, such as neodymium-doped amorphous glasses. Recently, we have achieved 50 TW peak power [5] using a hybrid Ti:Sapphire / Nd silicate glass beam line. But in the same work we did show that spectral gain narrowing in glass limited the pulse to duration above 450 femtoseconds. In the present work we demonstrate new concepts of generation and improvements in the techniques of measurements which allow to produce and fully characterize 30 TW pulses with duration as short as 260 fs and focus them on targets to get intensities above 2. 10¹⁹ W/cm².

© 1994 Optical Society of America