Coupled dye laser modes: experimental study of the dynamics

As a step towards the understanding of the phenomenon of pattern formation in high Fresnel number (#F) dye lasers, we experimentally study the system of two active regions sharing the same cavity. For separations of about 1-2 diameters of the active regions, the most conspicuous effect is a spectral shift, which is explained by a simple model of the molecular level populat ions. Discontinuous phase transitions, apparently the same found in coupled VCSELs, an observed simultaneously with spectral fluctuations. Phase locki ng is observed for separations of up to 16 diameters (#F approximate to 100 0), which leads us to conjecture that some mechanism of mode coupling addit ionally to the overlap of the diffracted fields must exist in dye lasers. ( C) 1999 Published by Elsevier Science B.V. All rights reserved.