Two-step pulse compressor based on asymmetric four-grating compressor for femtosecond petawatt lasers

Laser-induced damage of compression gratings has become the shortest stave for petawatt (PW) laser facilities, as it is hard to manufacture large enough meter-sized gratings with high damage threshold. Multistep pulse compressor (MPC) was proposed to improve the peak power of PW lasers recently. Using the asymmetric four-grating compressor (AFGC) to replace both of the prism-pair-based pre-compressor and typical four-grating compressor (FGC)-based main compressor, the typical three-step MPC is simplified to two steps, and can be easily extended to all PW lasers by simply reducing and increasing same amount of suitable distances of the two grating pairs, respectively. Furthermore, the AFGC will induce spatial dispersion and direct smooth the laser beam on the last grating, which is the easiest to be damaged one, and then protect it away from damage and increase the operating safety straightly. More than 100 PW can be achieved without beam combination theoretically using the AFGC-based two-step MPC method with currently available biggest gold-coated gratings.