✍ Scribed by Dr. Stefan Kirstein; Prof. Helmuth Möhwald
No coin nor oath required. For personal study only.
deconvolved duration is about 300 fs. Considering the dispersion effects in the detection setup, the lengthening compared to the readout pulse is reasonable. The rephasing of the pulse clearly happens only at the programmed delay. It must be emphasized that the three delayed pulses are recorded independently, therefore arbitrary delays can be chosen.
In conclusion, it was demonstrated that a thin film of spectral hole-burning material (PVB doped with chlorin) can serve as a highly spectrally selective, linear filter for ultrashort laser pulses. The requirement to the filter material is a large ratio of the width of the inhomogeneously broadened absorption band to the width of the zero phonon lines of the photochromic molecules in the polymer matrix. Different porphyrin and phthalocyanine derivatives as well as different polymer matrices were used with similar success. Thus the working wavelength of the filter could be shifted to the region of the output of the Ti: sapphire laser. Both phase and amplitude of the electrom.agnetic wave can be shaped. The restriction of their correlation due to the validity of dispersion relationships in the dielectric material were overcome by using a pulsed, holographic hole-burning technique (Fig. ). As a result the dispersion relationships even become an advantage, because they result in the correct phase once the amplitude is chosen. It was shown that spectrally selected parts of a 200 fs pulse can be coherently recombined to a desired time domain signal (Fig. ). With appropriate hologram shapes periodic pulse sequences up to several hundreds of ps duration can be achieved with pulse repetition rates in the order of 1 THz and pulse durations of 300 fs. Furthermore, by covering the total spectral range of the filter and explicitly using the linearity of the hole-burning process several pulses at different, independent delays with respect to the readout pulse can be created (Fig. ).
📜 SIMILAR VOLUMES
It is demonstrated that the upper Hubbard band (UHB) can play an important role in the hopping conductivity; 2D geometry and vicinity of the metal-insulator transition emphasize this role. A simple model for the recently observed metal-insulator transition is suggested. The model starts from the ins