Bistability, regular self-pulsing, and chaos in lasers with external feedback

Steady states and dynamic behavior of the light field in a lasing medium contained in the cavity of a Fabry-Perot (FP) resonator are investigated theoretically. The FP resonator is optically coupled to an external resonator (ER), which reflects light back into the laser within a small frequency interval. It is assumed that the lasing threshold cannot be exceeded without feedback from the ER. The losses of the compound-cavity system depend on the light frequency's giving rise to dispersive bistable effects. The static hysteresis cycle as well as transients between its branches has been calculated. Moreover, various types of regular and chaotic self-pulsing that are due to the oscillation of several modes of the compound-cavity system have been found, depending on the ratio of longitudinal relaxation time T(1) to the photon round-trip time T. Finally, phase modulation and frequency chirping have been determined.