An analysis is made of the evolution of a light pulse in a two-level resonant medium as a function of the degree of preliminary excitation by another pulse. It is shown that, in addition to self-induced transparancy observed under certain conditions associated with the degree of excitation of the atomic system, resonance scattering is also found due to the existence of macroscopic polarization of the medium. This scattering is not observed when the medium is in a noncoherent state. The transverse reversible relaxation time T*2 can be determined from the variation of the scattering intensity.

The propagation of the short light coherent pulse in a three-level resonant medium with a nonequidistant spectrum is analyzed as a function of the degree of preliminary excitation. It is shown, that the phenomenon like the stimulated Raman scattering (Stokes or anti-Stokes) should be observed under certain phase matching conditions besides the self-induced transparency and coherent Rayleigh scattering phenomena. The area theorem is obtained for all radiation components.

AbstractThe influence of the retarded part of Coulomb interaction between particles on the self‐induced transparency phenomenon is considered. This type of interaction is taken into account by introducing an effective dipole moment of an atom. Expressions for pulse area, absorption coefficient, and macroscopic medium polarization are derived. The area theorem is extended to include the retarded interaction. Estimates of the dipole moment and pulse delay are obtained. It is shown that the above parameters are substantially influenced by inhomogeneous broadening by the medium and the active centre concentration therein.

A change in the shape of short relatively weak laser pulses, leading to an apparent acceleration, was observed. The effect occurred during propagation of ruby laser pulses in Rb2 vapor in thermodynamic equilibrium at 200°C. A comparison of the theory with the experimental results yielded the modulus of the matrix element of the dipole moment of the resonance transition involved in this effect: The value of this modulus was 5 10–18 cgs esu.

A study of a system of N two-level molecules excited by a series of resonant laser pulses is made. Upon inversion such a system may give rise to coherent photon avalanches. If the system is irradiated with a subsequent pulse one should observe “light echoes” whose intensity is proportional to the square of the density of dipole moments of the system.

The scheme of a generator and detector of coherent gravitational radiation is investigated, when the energy transitions, in two, three etc. particles simultaneously are considered.