Accumulation effect in transient electronic stimulated Raman scattering accompanying pumping by a train of ultrashort pulses

Investigations were made of the accumulation effect exhibited by transient electronic stimulated Raman scattering in atomic barium vapor pumped by a train of ultrashort pulses with a controlled time delay between the pulses. The essential feature of the accumulation effect is that the Stokes energy of a pulse is contributed to not only by its own exciting pump pulse, but also by the previous pump pulse, the influence of the latter depending strongly on the ratio of the transverse relaxation time T₂ to the interpulse time interval. If one is to observe the accumulation effect in electronic stimulated Raman scattering, it is important to minimize the influence of depletion of the number of atoms. A method based on the accumulation effect for determination of T₂ in one laser shot was developed.