Stimulated photon echo at the transition 0–1 in ytterbium vapour: circular polarizations

For the first time, stimulated photon echoes (SPE) generated in a gas at the transition 0↔1 by circularly polarized resonant radiation pulses were analysed both theoretically and experimentally. Experiments were performed for the inter-combination transition (6s2) 1S0↔ (6s6p) 3P1 of 174Yb (type 0↔1). The SPE generated by three radiation pulses of identical circular polarizations has the same circular polarization. When the second or the third exciting radiation pulse has a circular polarization opposite to that of the other two pulses, the SPE polarization coincides with that of the oppositely polarized pulse. Finally, when the first exciting radiation pulse has a circular polarization opposite to the circular polarizations of the second pulse and third pulse, the SPE does not appear either in pure ytterbium vapour or in its mixture with a heavy atomic buffer. (letter)