Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences
Temporal contrast directly affects the interaction between the ultraintense and ultrashort pulse laser with matter. Seed laser sources with broad bandwidth and high temporal contrast are significant for overall temporal contrast enhancement. The technique of cascaded nonlinear processes with optical parametric amplification (OPA) and second harmonic generation (SHG) is demonstrated for high temporal contrast seed source generation. Within 40 ps before the main pulse, the temporal contrast reaches over 10<sup>11</sup>. The pulse energy and duration of the high contrast pulse are 112 μJ and 70 fs, respectively. Considering its high beam quality and stability, this laser source can serve as a high-quality seed for Nd: glass-based ultraintense and ultrashort pulse laser facilities.