Locking bandwidth of optically injected Fabry-Perot semiconductor lasers for high injection strengths

The authors compare simulated results using a commercial software program with solutions of the rate equation (RE) and Fabry-Perot (FP) models of an optically injected FP semiconductor laser for high injection strengths (with injection ratios between the master and slave lasers above 0 dB). For linewidth enhancement factors (alpha-factors) of 0 and 3, the locking bandwidth is compared with the RE model and in the case of an alpha-factor of 0, the results are also compared with the FP model. It is found that the RE model for high injection strengths does not describe the locking bandwidth very well, whereas the FP model gives good agreement with our simulated results. Additionally, the longitudinal variation of optical power and electron concentration are shown for different injection strengths and different detuning values. For an alpha-factor of 3, the spatial variations of these properties become asymmetrical for higher injection strengths and with an increase in detuning, they are found to exhibit decreased fluctuations when the lower locking boundary is approached through the locking region. Therefore it is important to take spatial variation into account for high injection strengths.