Spectral characteristics of vertical-cavity surface-emitting lasers with strong external optical feedback

We study the spectral optical properties of vertical-cavity surface-emitting lasers (VCSEL's) in the presence of strong optical feedback from an external reflecting surface. When the feedback strength exceeds 1%, multicompound-cavity-longitudinal-modes are observed. The output spectral width increases significantly as the feedback increases. Besides the normal compound-cavity modes, high-loss compound-cavity modes are also observed for the first time. The experimental observations are well explained by a compound-cavity laser theory.<
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