Effects of intrinsic spontaneous-emission noise on the nonlinear dynamics of an optically injected semiconductor laser

The effects of intrinsic spontaneous-emission noise on the nonlinear dynamics of an optically injected semiconductor laser is quantitatively studied through a single-mode model. It is found that for periodic motions, the effect of this noise source is to kick phase points off the underlying deterministic limit cycle. When the noise is not too strong so that phase points can stay near the limit cycle, phase points execute Brownian-like motions. When the noise is very strong, or the convergent flow near the attractor is weak, noise instantly kicks phase points away from the attractor to a region where nonlinearity is very strong. Then the diffusional process is slower than a standard Brownian motion. For chaotic motions, the characteristic short-term predictability of chaos is destroyed with an increasing amount of noise. The chaotic motions near the periodic/chaotic boundary, as well as at some locations inside the chaotic region, are more susceptible to noise. This suggests that there may exist fine structures inside the chaotic region.