Experimental demonstration of selective compression of femtosecond pulses in the Laue scheme of the dynamical Bragg diffraction in 1D photonic crystals.

We present the experimental results of diffraction-induced temporal splitting of chirped femtosecond optical pulses under the dynamical Bragg diffraction in the Laue geometry. For the experiments we made a transparent, high quality porous-quartz based 1D photonic crystal composed of 500 layers. We demonstrate that a selective compression of pulses is observed in this case, that is only one pulse from the pair is compressed, while the second one is broadened. This selective compression effect is determined by the sign and the value of the chirp parameter of the input pulse, in agreement with the theoretical description.

Carbon nanowalls: the next step for physical manifestation of the black body coating.

The optical properties of carbon nanowall (CNW) films in the visible range have been studied and reported for the first time. Depending on the film structure, ultra-low total reflectance up to 0.13% can be reached, which makes the CNW films a promising candidate for the black body-like coating, and thus for a wide range of applications as a light absorber. We have estimated important trends in the optical property variation from sample to sample, and identified the presence of edge states and domain boundaries in carbon nanowalls as well as the film mass density variation as the key factors. Also we demonstrated that at much lower film thickness and density than for a carbon nanotube forest the CNWs yield one order higher specific light absorption.