Chaotic dynamics of an optically pumped NH3 multitransverse-mode ring laser

We have experimentally studied the dynamics of an optically pumped NH multitransverse-mode ring laser. We show that, because of the nonlinear interaction of transverse modes, the laser intensity output can be periodic, quasi-periodic, or chaotic. Depending on which transverse modes were involved in the interaction, two kinds of routes to chaos were observed in the laser. When four transverse modes interact, quasi-periodic chaos is found, whereas in the case when just two transverse modes with small frequency separation interact a period-doubling route to chaos at the mode beat frequency is observed. Metric properties of observed chaotic attractors were calculated