Analysis of external optical feedback on distributed-feedback semiconductor lasers above threshold

An analysis of external optical feedback based on distributed-feedback (DFB) semiconductor lasers above threshold is presented. It is based on a numerical model taking into account the longitudinal spatial hole burning (SHB) effect, which has been recently known to be an important phenomenon for DFB lasers above threshold. Numerical results for a typical index-coupled quarter-wave-shifted (QWS) DFB laser with a moderate coupling coefficient ( kappa L=3) are given. It was found that the SHB effect can affect the sensitivity to feedback for DFB lasers above threshold.<
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