Modeling the impact of compressor diffraction grating defects on the quality of femtosecond laser beams and possibilities for their correction

Using mathematical modeling, we studied the influence of defects in the Treacy compressor diffraction gratings on wavefront quality and compared the results with an analytical model. We obtained good qualitative agreement: distortions from substrate defects and writing-system aberrations add and lead to a noticeable reduction of the Strehl ratio in the focal plane. Modeling showed that the second and third compressor gratings contribute most to the degradation, and rotating these gratings by 180° about the normal can markedly improve or worsen the resulting wavefront. We demonstrate that an optimal grating orientation combined with adaptive optics substantially reduces unwanted effects and restores the beam’s high peak intensity. The practical significance of this work is the recommendation to account for and compensate largescale defects when designing and operating large apertures in chirped pulse amplification systems to ensure maximum peak intensity and stable compression in multi-petawatt lasers.