High efficient triple-passed optical parametric chirped pulse amplification

A triple-passed non-collinear optical parametric chirped pulse amplifier is presented. The signal was triple-passed amplified in a single nonlinear crystal by a long pump pulse, in which the signal and pump pulses of each pass were completely phase matched in the plane to have the maximum of the effective nonlinearity. The total net gain higher than 3.7107, single pulse energy exceeding 3.7mJ with fluctuations less than 3%rms, 30nm amplified signal spectrum and recompressed pulse duration of 82fs were achieved. With this system, the parametric fluorescence is less than 1% of the total output pulse energy when the pump intensity is 350MW/cm2.