Universal nanosecond range pulse contrast measurement for a kJ-class petawatt laser.

ABSTRACT

A single-shot measuring apparatus with optical limiting for temporal pulse contrast of kJ-class petawatt lasers in the nanosecond range is proposed. A temporal linear filter comprising an electro-optical switch, a polarizer, a temporal nonlinear filter composed of cascaded SHG crystals, and a dichromatic mirror are, respectively, used as an optical limiting apparatus for contrast measurement of nanosecond and picosecond pulses to improve dynamic range and temporal resolution. The apparatus has been applied to pulse contrast measurements at the SG-II petawatt facility, achieving a high dynamic range of 1010 and a fast time resolution of 107 ps in the 350 ns range. This technique can also be universally applied to the limiting of the main pulse of varying pulse widths to diagnose pre-pulses during generation and transmission.