Experimental research on chaos operation in a CO2 laser caused by the transverse effect of the light fields

Abstract

The instabilities of cw-0O2 laser have been the object of extensive investigation in the field of laser instabilities and chaos. It is well known that a chaos operation of a system requires at least three dynamical variables in phase-space. Therefore, the CO2 lasers used in chaos investigation are all supplied with either modulation or feedback to enlarge the phase-space dimensionality. Recently, it is come to be known that some instabilities maybe result from the transverse distribution of laser fiedl. When the transverse freedom degree is considered, theoatical analysis shows that the Maxwell-Bloch equations change obviously. Different simplified models have been discussed priliminarily, but to data no clear experimental demonstration has been given. Here we report our experimental studies on instabilities caused by the transverse effects. Chaos operation are first observed in a single-lingitudinal, multi-transverse mode cw-0O2 laser in the abscence of any kinds of modulation or feedback. The laser output evolves from stability to chaos along different routes when the laser parameter are changed. Our experiment shows that the transverse distribution of light field and population inversion is an important factor in causing laser instabilities.