Broadband amplification of 800-nm pulses with a combination of negatively and positively chirped pulse amplification

It is experimentally proved that successive amplification of negatively and positively chirped laser pulses (NPCPA) counteracts the gain narrowing effect typical in chirped pulse amplification (CPA) lasers. The scheme is robust and easy to adopt to even petawatt (PW) level high power laser systems. As a demonstration, a multi-terawatt (TW) Ti:sapphire laser system was modified to the NPCPA. The bandwidth of the 150 mJ output pulses exceeds 50 nm without any additional spectral correction, which is 30% broader than those currently available from conventional CPA lasers. Moreover, the NPCPA scheme gives an opportunity to increase an intensity temporal contrast without any compromise in pulse energy.