Numerical analysis of the feedback regimes for a single-mode semiconductor laser with external feedback

The effect of external feedback on a single-mode semiconductor laser is estimated by a numerical solution of the nonlinear rate equations, yielding an excellent description experimental results. It is found that the lasing mode with the minimum linewidth is most stable rather than the mode with minimum threshold gain. The transition to the coherence-collapse regime is of particular interest. It usually occurs for feedback fractions ≅ 10/sup -4/, but it may shifted to considerably larger feedback levels by either increasing the emitted optical power, the laser length, or by decreasing the linewidth enhancement factor α