Laser and Particle Beams

Research Article

Lasing properties and nonlinearities of dyes under high power pumping

M. Milania1, L. Ferraroa1, F. Causaa2 and D. Batania3 c1

a1 Department of Material Sciences, Milano-Bicocca University, Milan, Italy

a2 Department of Electronic and Electrical Engineering, University of Bath, UK

a3 Department of Physics, Milano-Bicocca University, Milan, Italy


Nitrogen lasers have been used for many years to make dye solutions lase. A nitrogen laser, which transverse electrical discharge in gas at atmospheric pressure has been built in our laboratory. It has been characterized and applied to pump different dyes: Rhodamine 6G, Coumarin 440, DOTCI, and pyranine in simple “on axis” geometric configuration. It has been shown that pyranine can lase in the absence of any optical external mirror cavity, this happens at very low threshold, and in different solvents. Dyes under consideration can be grouped into two major classes according to their lasing behavior independently on their concentration in the solvent: Rhodamine 6G and DOTCI can lase both axially or transversally and Coumarin 440 and pyranine can lase only axially. Other intriguing features have been observed that span from simultaneous multiple beam generation, to super fluorescence and to distribute axial pumping of dye solutions. A preliminary basis for understanding and controlling such processes is the spatial energy distribution and the energy density of the beam.

(Received February 04 2007)

(Accepted July 23 2007)


  • Dyes;
  • Lasing properties;
  • Laser radiation Nitrogen laser


c1 Address correspondence and reprint requests to: D. Batani, 1Department of Physics, Milano-Bicocca University, Milan, Italy. E-mail: