Theory of transient two-photon resonant up-conversion with non-synchronized excitation

T.B. O'Hare

Iu S, Hong Zhang

We have studied the two-photon resonant excitation and enhancement effect of a high excitation state 15d in Rb atom by using a synchronously pumped tunable mode-locked dye laser and obtained the frequency up-conversion at 1.065μm→4210 A. The relationship between self-phase matching and output of UV coherent radiation output is given. This paper emphasizes the study of the transient coherent effect and dephasing process of this state. It has been shown experimentally that the maximun polarized time by two-photon resonant excitation is 120 ps and UV coherent radiation could be induced under the action of probing signal until 350ps. However up to now no report has been declared about the study of trasient coherent dephasing in higher excitation states oi atom systems. All experimental set-ups, results, principle explanation are given.

J N Elgin, G.H.C. New, P. Smith

For pt.I see ibid., vol.11, no.19, p.8439 (1978). This is the second in a series of papers in which various theoretical aspects of two-photon resonant up-conversion with ultrashort pulses are examined. The first paper in the series was concerned with the case of third harmonic generation. The authors study the more general two-photon resonant four-wave process ( omega a + omega a )+ omega c to omega d for the case where the pulse at omega a is not time synchronised with the pulse at omega c .

M. M. T. Loy

N. A. Iskanderov, Vladimir A. Kudryashov, I. N. Matveev +1 more

Four-photon parametric up-conversion of a weak infrared signal under conditions of two-photon resonance of a constant nonmonochromatic pump field is analyzed allowing for population migration, transient response of the medium, Stark shift of the levels, and width of the pump frequency spectrum. It is found that under steady-state conversion conditions in a nonmonochromatic pump field, it is possible to achieve an average conversion efficiency differing only negligibly from the maximum conversion efficiency in a monochromatic pump field. An analysis is made of the influence of optically induced relaxation on the average conversion efficiency in the transient regime. Numerical estimates are made of the transition parameters for an alkali metal vapor in a frequency-degenerate pump field exciting a two-photon transition.

A. K. Popov, V. P. Timofeev