Abstract

Research for nonlinear dynamics in optical system has evolved from simple instabilities in single mode oscillation to complicated phenomena in multimode oscillation, such as spatial pattern formation, optical voltices, chaotic itineracy,¹ spot dancing, synchronization of chaos² and etc. Among them, the laser with a saturable absorber (LSA) has revealed various aspects of nonlinear dynamics from a single mode self-sustained regular pulsation to multimode chaotic oscillation. Above all, type-B laser like CO₂ laser, in which the degree of polarization can be adiabatically eliminated, has a remarkable advantage of describability with rate equation approximation. We have reported⁵ that regular mode-switching and two distinctive types of chaos exist in a bimode CO₂ LSA. One type was identified by the period doubling route to chaos and the fractal dimension of the strange attractor was calculated to be 2.02 ± 0.02. The other was identified by the abrupt transition from the regular oscillation to chaos, where the fractal dimension was calculated to be 2.47 ± 0.01. In this paper we report precisely the route to chaos in the latter case.

© 1995 IEEE