Bifurcation to mixed external cavity mode solutions for semiconductor lasers subject to optical feedback

The Lang and Kobayashi equations modeling a semiconductor laser subject to optical feedback admit time-periodic solutions which are combinations of tw o distinct external cavity modes. We construct these solutions analytically and show that they emerge and disappear at two distinct Hopf bifurcation p oints. These mixed external cavity mode solutions exhibit interesting high frequency time-periodic intensities. Furthermore, they undergo a secondary bifurcation to quasiperiodic oscillations which we investigate numerically. Our analysis complements earlier investigations by Tager and Peterman (IEE E J. of Quant. Electron. 30 (1994) 1553) and provide a first explanation of recent experimental observations for a diode laser subject to two optical feedbacks. (C) 2000 Elsevier Science B.V. All rights reserved.