Controlling the coherence properties of quantum dot superluminescent light emitting diodes via frequency selective optical feedback

In low coherent light interferometry (OCT) broad bandwidth light sources are required to achieve high axial resolution. Here superluminescent light emitting diodes (SLEDs) utilizing quantum dot (QD) gain materials are promising devices as they unify large spectral bandwidths with high power at desired emission wavelengths. However, due to the spectral dot dynamics, dips in the optical spectrum occur that lead to parasitic coherence peaks in the interferogram. We apply frequency selective feedback to increase the output power and to shape the spectrum, hence optimizing the coherence properties of the QD-SLEDs.