We report on design, production and characterization of an extremely broadband multilayer beamsplitter, covering wavelength range from 0.67 - 2.6 µm. The group delay dispersion has small oscillations in the above mentioned working range. We used a new algorithm with floating constants allowing us to obtain a smooth and near constant GDD. The optical element based on the beamsplitter is used for dividing a low-energy super-octave spectrum into several sub-spectral regions which are later amplified and coherently combined.