Influence of external optical feedback on threshold and spectral characteristics of vertical-cavity surface-emitting lasers

We report a study of the effects of external optical feedback on the threshold and spectral characteristics of VCSELs with feedback levels in the range from /spl minus/25 dB to 0 dB. A large threshold current reduction and multi-extended-cavity-mode operation have been observed. The experimental results are in good agreement with the theoretical calculations based on a compound cavity laser model.<
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