Wavefront measurement of yoked superfluorescence

Kenta Kitano, H. Maeda

Zhenhuan Yi, Pankaj K. Jha, Luqi Yuan +7 more

Ariunbold Gombojav, Vladimir A. Sautenkov, Marlan O. Scully

Kenta Kitano, H. Maeda

Kenta Kitano, H. Maeda

We investigated both spatial and temporal profiles of the 420-nm yoked superfluorescence (YSF) from the atomic vapor of rubidium by driving the $5S\ensuremath{-}5D$ two-photon transition with an ultrashort laser pulse. By increasing the pump-pulse power beyond the saturation intensity, the spatial profile of the 420-nm YSF periodically changed between a central bright spot and a ring-shaped radial profile. The temporal profile of the 420-nm YSF was measured with a sampling oscilloscope with a time resolution of 50 ps. The experimental results were successfully reproduced by simulations using the Maxwell-Bloch equations. The simulated results confirmed that, in the strong excitation regime, the 420-nm emission from the lower transition component of the YSF is significantly delayed with respect to the 5.2-$\ensuremath{\mu}\mathrm{m}$ emission from the upper transition, while they are overlapped in the weak excitation regime.

Alexander I. Lvovsky, Fred Moshary, Sven R. Hartmann

Summary form only given.We have observed yoked superfluorescence (YSF) on the 5D-6P-5S channel in atomic rubidium after two-photon excitation of the 5D-5S transition by a short (3 ps), 778-nm pulse from a Ti:sapphire laser system. The excitation pulse is formed by a pair of spatially overlapping pulses of wave vectors k/sub 1/ and k/sub 2/ where |k/sub 1/|=|k/sub 2/|=2/spl pi///spl lambda/ and /spl lambda/ is the wavelength of the 5D-5S transition. When the atoms are excited by taking one photon from along k/sub 1/ and one from along k/sub 2/, then phase matching requires that the yoked transition consists of photon pairs along k/sub DP/ and k/sub PS/ where k/sub 1/+k/sub 2/=k/sub DP/+k/sub PS/ and k/sub DP/ and k/sub PS/ are the wave vectors of, respectively, the upper (5D-6P) and the lower (6P-5S) transition components of the YSF. The YSF pulses are emitted in a cone determined by Brownell et al. (1995). This conical emission of YSF was observed on the 420 nm lower transition. The measured behavior of the conical apex angle /spl beta/ as a function of the angle between the excitation pulses /spl alpha/ is given as a series of points and shows good agreement with the solid line based on Brownell et al.