Effect of Noise on the Bifurcations to Chaos in a Modulated Diode Laser

It has been demonstrated theoretically that a diode laser, when directly modulated at a rate comparable to its relaxation oscillation frequency, exhibits a period-doubling route to chaos1. This prediction was based on a numerical solution of the deterministic noise-free rate equations that govern the interaction between electrons and photons in the laser. However, it is known that the output of a cw diode laser can exhibit large amplitude fluctuations with a frequency centered at the relaxation oscillation resonance2. These fluctuations arise from the quantum nature of spontaneous emission and cannot be eliminated in real diode lasers. In effect, the laser acts as a noise-driven relaxation oscillator. In this paper we consider the effect of quantum noise on the predicted bifurcations to chaos of directly modulated diode lasers.