Visible superfluorescence from optically pumped europium atoms
Spectroscopy Division, Bhabha Atomic Research Centre, 400 085 Mumbai, India
Corresponding author: a email@example.com
Revised: 20 May 2009
Published online: 30 June 2009
We have observed superfluorescence (SF) on five atomic transitions at visible wavelengths 633.58, 635.00, 640.09, 640.61 and 736.22 nm in Doppler broadened gas of europium (Eu) atom. The nanosecond SF pulses were observed by longitudinally pumping Eu vapor column with a pulsed dye laser to upper states 4f65d6s2, 8D7/2 at 346.79 nm and 4f75d6p, 10F5/2 at 348.73 nm from the ground state 4f76s2, 8S7/2. High optical conversion efficiency ≈10% was measured for these SF transitions. Our experiment deals with the large sample multilevel SF in the regime where the length of the excited column L is greater than the maximum value of the Arecchi-Courtens length (Lc). The observed variation of SF peak intensity (Ifl) and time delay for SF evolution (τD) with number of atoms in the excited state (N) resemble theoretically predicted SF scaling laws for transverse excitation, namely Ifl ∝N and although the experimental condition is similar to the swept excitation. This could be due to the Rabi frequency associated with the pump transition which is comparable to the SF delay time precluding the initiation of SF at different times along the sample and results in transverse (instantaneous) excitation. The experimental τD values were found to be in agreement with the quantum mechanical calculations describing SF.
PACS: 42.50.Nn – Quantum optical phenomena in absorbing, amplifying, dispersive and conducting media; cooperative phenomena in quantum optical systems / 42.50.Gy – Effects of atomic coherence on propagation, absorption, and amplification of light; electromagnetically induced transparency and absorption
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2009