Pulse compression and beam focusing with segmented diffraction gratings in a high-power chirped-pulse amplification glass laser system

摘要

Segmented (tiled) grating arrays are being intensively investigated for petawatt-scale pulse compression due to the expense and technical challenges of fabricating monolithic diffraction gratings with apertures of over 1 m. However, the considerable freedom of motion among grating segments complicates compression and laser focusing. We constructed a real compressor system using a segmented grating for an 18 cm aperture laser beam of the Gekko MII 100 TW laser system at Osaka University. To produce clean pulse shapes and single focal spots tolerant of misalignment and groove density difference of grating tiles, we applied a new compressor scheme with image rotation in which each beam segment samples each grating segment but from opposite sides. In high-energy shots of up to 50 J, we demonstrated nearly Fourier-transform-limited pulse compression (0.5 ps) with an almost diffraction-limited spot size (20 (mu)m).