Ultra-high contrast frontend for high peak power fs-lasers at 1030 nm

We present the results from a new frontend within a double-chirped pulse amplification architecture (DCPA) utilizing crossed-polarized wave generation (XPW) for generating ultra-high contrast, 150 mu J-level, femtosecond seed pulses at 1030 nm. These pulses are used in the high energy class diode-pumped laser system POLARIS at the Helmholtz Institute in Jena. Within this frontend, laser pulses from a 75MHz oscillator-pulse train are extracted at a repetition rate of 1Hz, temporally stretched, amplified and then recompressed reaching a pulse energy of 2 mJ, a bandwidth of 12 nm and 112 fs pulse duration at a center wavelength of 1030 nm. These pulses are temporally filtered via XPW in a holographic-cut BaF2 crystal, resulting in 150 mu J pulse energy with an efficiency of 13%. Due to this non-linear filtering, the relative intensity of the amplified spontaneous emission preceding the main pulse is suppressed to 2x10(-13). This is, to the best of our knowledge, the lowest value achieved in a high peak power laser system operating at 1030 nm center wavelength. (C) 2014 Optical Society of America