We have demonstrated broad bandwidth large area (229 mm x 114 mm) multilayer dielectric diffraction gratings for the efficient compression of high energy 800 nm laser pulses at high average power. The gratings are etched in the top layers of an aperiodic (Nb0.5Ta0.5)2O5-SiO2 multilayer coating deposited by ion beam sputtering. The mean efficiency of the grating across the area is better than 97% at the center wavelength and remains above 96% at wavelengths between 820 nm and 780 nm. The gratings were used to compress 5.5 J pulses from a Ti:sapphire laser with an efficiency above 80 percent.

We have demonstrated broad bandwidth large area (229 mm x 114 mm) multilayer dielectric diffraction gratings for the efficient compression of high energy 800 nm laser pulses at high average power. The gratings are etched in the top layers of an aperiodic (Nb 0.5 Ta 0.5) 2 O 5-SiO 2 multilayer coating deposited by ion beam sputtering. The mean efficiency of the grating across the area is better than 97% at the center wavelength and remains above 96% at wavelengths between 820 nm and 780 nm. The gratings were used to compress 5.5 J pulses from a Ti:sapphire laser with an efficiency above 80 percent.

We investigate the variations that occur with changes in the number of layers and with the use of the assist beam main and assist beam energy on the morphology of HfO 2 /SiO 2 quarter wave stacks deposited by dual ion beam sputtering. We show how the addition of sequential HfO 2 /SiO 2 bilayers, up to eight, affects the surface roughness and micro-crystallinity of the top HfO 2 layer. We also show that use of the assist source significantly smooths the surface while simultaneously reducing microcrystallinity. The HfO 2 /SiO 2 structures are very robust and can withstand fluences in excess of 3 J/cm 2 generated by 1ps pulses from a chirped amplified Ti:Sapphire laser.

No abstract

The single pulse femtosecond laser induced damage threshold (LIDT) of hafnia and silica films is not affected by the ambient gas pressure. In vacuum, the multiple pulse LIDT drops to ~10% (~10%) of its atmospheric value for hafnia (silica). The water vapor content of the ambient gas was found to control the change in the LIDT. The LIDT of bulk fused silica surfaces did now show any dependence on the ambient gas pressure. Hydrocarbons (toluene) did not change the multiple pulse LIDT for Hafnia films