PGL has been supplying MLD gratings to many of the world’s largest ultrahigh- intensity laser installations for over a decade. The combination of thin-film coating with grating design and fabrication makes it possible to greatly improve diffraction efficiency, laser damage threshold, and wavefront of the compressed short pulse.
Gratings for pulse compression have very demanding requirements – in addition to severe flatness and damage threshold requirements, they must operate in high vacuum. With coatings of up to 40 layers in these conditions, coating stress must be carefully controlled, since too much compressive stress deforms the substrate while too much tensile stress causes “crazing.” PGL has developed a low-stress coating process for MLD gratings that achieves exceptional uniformity over very large areas and enables superior all-around performance under a wide range of operating conditions.
PGL has extensive expertise in grating manufacturing, as well as in thin-film optical coating, reactive-ion etching, optical metrology, and precision cleaning, inspection, and handling of large optics. All of these process areas are critical to high-performance MLD diffraction gratings.
PGL MLD gratings have demonstrated both high diffraction efficiency and high damage threshold. Our meter-class gratings consistently achieve > 96% diffraction efficiency in the 1st order, and LIDT is proven at both 600 fs and 10 ps – the results are among the highest ever demonstrated for MLD gratings.
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