Experimental results are reported on the coherence properties and low frequency noise of index-guided AlGaAs diode lasers with optical feedback. The coherence length, Lc, of the laser field is strongly dependent on the amount of feedback and feedback phase, provided Lc is larger than twice the external cavity length. A coherence collapse is observed for high levels of op-tical feedback. Three excess noise peaks have been observed and are attributed to external cavity mode - and diode cavity mode hopping. The results will be discussed using a theoretical analysis for the nearly-coherent feedback and fully-incoherent feedback cases.
B. H. Verbeek, B. H. Verbeek,
"Coherence Properties and L.F. Noise in AlGaAs Lasers with Optical Feedback", Proc. SPIE 0587, Fiber Optic Sources and Detectors, (9 July 1986); doi: 10.1117/12.951206; https://doi.org/10.1117/12.951206