Reduced photon bunching in cooled quantum dot superluminescent diodes

Quantum dot superluminescent diodes provide large optical bandwidths with high output power at desired emission wavelengths and are therefore suitable devices for high resolution depth imaging in low coherent light interferometry. At high pump currents QD SLDs emit amplified spontaneous emission (ASE), where a large fraction of spontaneously emitted photons gets amplified by stimulated emission. These ASE photons obey Bose-Einstein statistics, where g²(τ) for zero time delay exhibits a value of g²(0) = 2, reflecting the tendency of photons to arrive in bunches. Inevitably, this photon bunching is related to large intensity fluctuations that often become a limiting factor in the application of QD SLDs. This paper demonstrates that modifications in the thermal coupling of the QDs provide a way to reduce these fluctuations.