Abstract

The development of laser chains based on the Chirped Pulse Amplification leads now to peak powers higher than 100 TW. The focused intensity can reach 10²¹ W/cm². To keep the laser matter interaction in the femtosecond regime, the pulse has to exhibit a high temporal contrast. The most important problem consists in the presence of an Amplified Spontaneous Emission (ASE) background coming from the amplification process. At the output of the laser the ratio between the femtosecond pulse intensity and the ASE level is about 10⁶ leading to an ASE intensity as high as 10¹⁵ W/cm², far above the ionization threshold of most materials and susceptible to strongly modi- fy the interaction process.

© 2001 Optical Society of America