Femtosecond laser damage of broadband pulse compression gratings

The fabricated gratings used for an 800-nm compressed laser pulse have more than 90% di?raction e?ciency in the –1st order for TE polarization within 760–860 nm, and the maximum value is 94.3%. The laserinduced damage threshold(LIDT) of the gratings increases from 0.53 to 0.75 J/cm 2 in the normal beam in a pulse width τ of 40–100 fs. The LIDT of the gratings is observed a τ 0. 25 scaling in the pulse width region. The damage morphologies of the gratings indicate that the initial damage of the gratings locates at the grating lines, a position that coincides with that of the electric field maximum.

Specifications and control of spatial frequency errors of components in two-beam laser static holographic exposure for pulse compression grating fabrication

The large-aperture pulse compression grating(PCG) is a critical component in generating an ultra-high-intensity, ultra-short-pulse laser;however, the size of the PCG manufactured by transmission holographic exposure is limited to large-scale high-quality materials. The reflective method is a potential way for solving the size limitation, but there is still no successful precedent due to the lack of scientific specifications and advanced processing technology of exposure mirrors. In this paper, an analytical model is developed to clarify the specifications of components, and advanced processing technology is adopted to control the spatial frequency errors. Hereafter, we have successfully fabricated a multilayer dielectric grating of 200 mm × 150 mm by using an off-axis reflective exposure system with Φ300 mm. This demonstration proves that PCGs can be manufactured by using the reflection holographic exposure method and shows the potential for manufacturing the meter-level gratings used in 100 petawatt class high-power lasers.