<title>Femtosecond photon echo in dye-doped polymer film at liquid nitrogen and room temperatures</title>

Abstract

The first observation is reported of the primary and stimulated femtosecond photon echoes at liquid nitrogen and room temperatures in a dye-doped polymer film at a wavelength of 780 nm. Echo signals were generated by pulses with the duration of 130 fs. The primary echo signal decay at a liquid nitrogen temperature can not be described by a simple exponential function. There is a fast decay region below 250-300 fs and a slow decay region at longer time intervals. The decay of primary echo signal at room temperature demonstrates complex behavior caused by the presence of the phonon-side band in the optical band of impurity centers. There were also detected signals of the self-diffraction of exciting pulses on a nonequilibrium population difference grating, induced in resonant medium by these pulses.