The spatial distribution of the optical parametric fluorescence generated in a negative uniaxial nonlinear crystal is asymmetric with respect to the pump when the pump beam has a slight divergence angle. The formation mechanism of this phenomenon and the influence of parameters were analyzed and discussed from a theoretical standpoint. Moreover, two potential applications of this phenomenon were experimentally demonstrated, showing the temporal contrast improvement of ultra-intense lasers and the intensity enhancement of special light sources induced by the optical parametric generation.

The mechanism of suppressing optical parametric fluorescence (OPF) with a quencher pulse in an optical parametric chirped-pulse amplification (OPCPA) laser is investigated. A simplified theoretical model of this phenomenon is presented, and numerical simulations and experimental demonstrations are performed for explanation and verification. The results show that, although the improvement of the temporal contrast usually is limited, the generation and amplification of the OPF in an OPCPA process does be suppressed by the injection of a quencher pulse, and the suppression capability can be slightly enhanced by increasing the quencher-pulse energy. We believe that this work will be helpful in designing high-peak-power lasers with high temporal contrast.