Root-locus technique for predicting the stability of laser diodes with optical feedback

Summary form only. The work presented in this paper gives a novel procedure for calculating the allowable range of external feedback regardless of the external cavity length. The method is an extension of the root locus technique used in control system design. A simple calculation yields the locus of the positions of the dominant s-plane poles of the laser transfer function as the feedback strength and cavity length are varied. The feedback strength which forces the locus into the unstable right half-plane is thus the maximum allowable feedback strength before the system dynamics become unstable and chaotic.