ИСТИНА

In the present work, an innovative optical element developed for the multiterawatt few-cycle light wave synthesizer based on optical parametric amplification is demonstrated. The synthesizer currently produces sub-5-fs, 80-mJ, 18-TW pulses. The required element had to be deposited on 15 mm substrate having 75 mm in diameter; an average value of the GDD of +75 fs2 and reflectance exceeding 99% in the spectral wavelength region from 570 to 1030 nm. Mechanical stresses of the designed dispersive mirror (DM) caused the substrate bending that distorts wave front quality resulting in the distorting of the beam waveform of laser system. In order to compensate this mechanical stress, the substrate back side was covered by an antireflection coating providing the lowest possible reflection in the working spectral range, having the total physical thickness close to DM thickness and total thicknesses of Nb2O5/SiO2 layers close to the corresponding total thicknesses of Nb2O5/SiO2 in DM. The produced DM-AR optical element exhibits excellent spectral properties