Abstract

Many high intensity laser experiments rely on high temporal intensity contrast. However, this is difficult to achieve due to scattering, coherent contrast, amplified spontaneous emission or internal reflections [1]. Even minute artifacts (8-9 orders of magnitude smaller) can ionize the target nanoseconds prior to the arrival of the main beam. Common strategies for post amplifier contrast improvement rely on intensity dependent nonlinearities, either by single-shot plasma mirror setups or a nonlinear crystal for second harmonic generation. While plasma mirrors obtain 2-3 orders of contrast improvement prior to the triggering intensity threshold, scales second harmonic contrast enhancement with the intensity squared. Second harmonic generation in Petawatt laser have been reported previously with longer pulses and sub-aperture [2] or with less energy [3]. We report here on theoretical and experimental results for boosting the temporal contrast of the Texas petawatt laser [4] by a second harmonic generation setup.

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