Stability properties of the monochromatic spectrum in a double-cavity laser

We discuss the process by which the spectrum of monochromatic modes of the laser in a double-cavity laser changes from that proper to a shea cavity into that proper to a long cavity as the reflectivity of the "external'' mirror is varied from 0 to 1. This work is the natural continuation of our previous work [Phys. Rev. A 58, 614 (1998)], where the bifurcations occurring during this metamorphosis were studied. The transformation is mostly dictated by the boundary conditions and occurs regardless of the laser model. This transition is beyond the possibilities of simpler double-cavity laser models, such as those of Lang and Kobayashi [IEEE J. Quantum Electron. QE-16, 347 (1980)]. The stability properties of the monochromatic modes are studied as a function of the reflectivity of the external mirror R, the external cavity length L, and the applied current J. It is shown that for reflectivity values corresponding to the metamorphosis of the spectrum, by varying J and/or R, the system can give rise to a Hopf instability that involves the excitation of a roughly discrete set of frequencies. Note that these features are also beyond the possibilities of simpler models. We also discuss the role played by noise and show that it is possible for the system to show a high degree of susceptibility to noise, depending on J. [S1050-2947(99)10608-5].