Temporal coherence characteristics of a superluminescent diode system with an optical feedback mechanism

We explore the temporal coherence characteristics of the output light of a SLD system with different optical feedback ratios by a Michelson interferometer, and we also observe the long-scan-range interference patterns with the one by one wave packets due to the Fabry-Perot modulation of the SLD device. We can obtain the effective cavity length of the SLD active layer and get more information of the temporal coherence length or spectral width from the long-scan-range interference patterns. This tunable light source system can provide more insights into the optical coherence or lasing phenomena often discussed in the optics course.