Abstract:The results of an experimental investigation of the incoherent photon echo in ruby (with Cr 3+ concentration equal to 0.16 wt%) at T = 1.7 K are presented. Optical fiber with length 3 m and diameter 100 µm was used for delivery of the first exciting pulse to a sample. The dependence of the IPE intensity on the excitation wavelength within the width of R1 absorption line was studied. The IPE decay curve was obtained and the phase relaxation time was found to be equal to 98 ns. Oscillogram of incoherent backward photon echo (IPE) in concentrated ruby. The IPE signal is the first one at the right. The other pulses are the signals of diffraction corresponding to the first and the second exciting laser pulses

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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 65 fs. The primary echo signal decay at liquid nitrogen and room temperatures can not be described by a simple exponential function. 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.Photos of "traces" on the screen caused by exciting pulses (strong "traces"), by primary femtosecond photon echo (the upper weak "trace" at the right in photo (a)), stimulated femtosecond photon echo (the lower weak "trace" at the right in photo (a)) and by signals of self-diffruction (weak "tarces" in photo (b))

Abstract:The first observation is reported of the primary femtosecond photon echo at a liquid nitrogen temperature in a dyedoped polymer film at a wavelength of 780 nm. Echo signals were generated by pulses with the duration of 130 fs. The echo signal decay 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. 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. Photos of "traces" on the screen caused by exciting pulses, by the PFPE signal and by signals, corresponding to the first order of self-diffraction

Two-pulse, stimulated and accumulated photon echoes are investigated for the first time in a highly doped crystal Tm:YAG containing 10 at.% Tm 3+ . The decay curves of the two-pulse and stimulated photon echoes generated at 793.15 nm on the transition 3 H6(1)-3 H4(1) of the impurity ions are measured in the absence of an applied magnetic field and parameters describing the energy and phase relaxation are determined. The dependence of the intensity of the accumulated photon echo on the number of excitation pulse pairs is investigated.Echo intensity, a.u. Delay time τ 23 , msThe decay curve of stimulated photon echo in Tm:YAG (10 at.%)