Comprehensive experimental evaluation of temporal contrast enhancement techniques applied to the petawatt-class J-KAREN-P laser system

Abstract

We present a systematic experimental investigation of temporal contrast enhancement techniques for petawatt (PW)-class Ti:sapphire lasers utilizing a double chirped-pulse amplification (CPA) architecture. Particular attention is given to pre-pulses induced by post-pulses originating in the first CPA stage. One conventional and two advanced pulse-cleaning strategies are quantitatively evaluated: (i) a saturable absorber (SA), (ii) a femtosecond optical parametric amplifier (OPA) employing the idler pulse in a two-stage configuration, and (iii) sum-frequency generation (SFG) combining the signal and idler pulses from the OPA. All techniques are implemented and evaluated using the J-KAREN-P laser system with an output energy of about 20 J. To the best of our knowledge, this is the first report to directly and systematically compare the contrast of pre-pulses originating from the first CPA stage under identical experimental conditions in a high-energy PW-class laser facility. The results offer crucial insights into contrast optimization for future high-field applications.