Numerical characterization of intensity and frequency fluctuations associated with mode hopping and single-mode jittering in semiconductor lasers

This paper reports on numerical characterization of intensity and frequency fluctuations associated with mode hopping and single-mode jittering in semiconductor lasers. A new numerical approach has been applied that takes into account the suppression effects of gain and the intrinsic fluctuations in both intensities and phases of the oscillating modes. The temporal trajectories of mode intensities are investigated. The fluctuations are characterized in terms of their correlation functions and statistical distributions. The intensity and frequency noise contents of fluctuations are also identified. The obtained characteristics are compared with those of stable single-mode operation (SSMO) in nearly-single-mode lasers. The case of multi-mode hopping in multi-mode lasers is also analyzed. The cross-correlation analyses confirm strong anti-correlations among intensity fluctuations of the hopping and jittering modes. The relative intensity noise (RIN) in both total output and modes are most enhanced under mode hopping, and so is the frequency noise (FN). Although the jittering operation induces lower noise levels in the low-frequency regime, the noise is higher than the quantum level characterizing the SSMO. The cross-correlations among the hopping modes are stronger and the intensity noise levels are higher in the case of two-mode hopping in nearly-single-mode lasers than those in the case of multi-mode hopping in multi-mode lasers. The explored characteristics are compared with the experimental observations. (C) 2002 Elsevier Science B.V. All rights reserved.