Coherent and thermal light: Tunable hybrid states with second-order coherence without first-order coherence

We demonstrate the realization of a new hybrid state of light that is simultaneously spectrally broadband, i.e., in-coherent in first order, and exhibits a laserlike normalized intensity correlation coefficient of 1.33, reflecting high coherence in second order. This is achieved by temperature-tuned light emission from an optoelectronic quantum dot superluminescent diode where the condensation of injected charge carriers into the globally lowest energy state of the strongly inhomogeneously broadened semiconductor quantum dot ensemble gives rise to a particular balance between spontaneous and stimulated emission.