Superfluorescence from europium atom at 629.977Â nm

Visible superfluorescence at 629.977 nm is observed in europium atom with very high optical conversion efficiency on the transition 5d6p 10F7/2 → 5d6s 10D7/2. The peak intensity of fluorescence varies as square of the number of atoms in the excited state (N), which shows the superfluorescence character of the transition. The ratio of average superfluorescence power to excitation laser power is observed to be ∼15% in the forward direction.