Diffraction gratings for lasers with pulse compression: comparative research

Diffraction gratings are key elements of laser systems with pulse compression. For providing of high peak power subpicosecond pulses these gratings should have a high damage threshold, large aperture and high optical quality. In the present work comparison holographic and ruled gratings for systems of pulse compression is spent. Ruled gratings had spatial frequency 1740 grooves/mm, and holographic - 1700 grooves/mm and were covered by gold, that provided 90 % diffraction efficiency to the first diffraction order. Measurements of damage thresholds for 1 ps and 0.5 ns pulses have shown that for ruled grating it more than for holographic. It was probably connected to a thicker layer of metal for ruled gratings. To increase of a grating's damage threshold additional multi layer dielectric coatings were used. Computer calculations have shown that by changing of amount, material and thickness of layers it is possible to significantly improve damage thresholds. Experimental measurements have shown that for four layers there is the increase of thresholds in 2 times. Received thresholds show, that for the being available sizes as ruled (170x170 mm), and holographic (200x400 mm) gratings generation of multyterrawatt laser pulses in CPA laser systems is possible.