Authors: Aßmann, Marc
Title: Photon Statistics of Semiconductor Light Sources
Language (ISO): en
Abstract: In recent years, semiconductor light sources have become more and more interesting in terms of applications due to their high efficiency and low cost. Advanced designs like lasing without inversion make it possible to approach the ideal so-called thresholdless laser. However, the drawback of such highly efficient light source lies in the rather complicated techniques needed to characterize the emission properties. While common laser emission above and below the lasing threshold can easily be distinguished just by analyzing the output power, the more sophisticated technique of characterizing the emission in terms of their coherence properties by Hanbury Brown-Twiss interferometry must be applied to characterize semiconductor lasers. This poses several problems. Coherence properties manifest in the emission photon statistics, but only on timescales shorter than the coherence time of the emission. While typical coherence times are still in the nanosecond range for common lasers operated below threshold, they are as short as a few tens of picoseconds for semiconductor lasers. This poses a problem as the most commonly used detectors to measure photon statistics are photodiodes which offer a temporal resolution of hundreds of picoseconds at best. This work discusses an alternative experimental approach to measure photon statistics using a streak camera. The best possible time resolution using this setup is shown to be on the order of two picoseconds and therefore sufficient for measurements on semiconductor lasers. This experimental technique is applied to several kinds of semiconductor-based light sources, including quantum-dot vertical-cavity surface-emitting lasers, planar microcavity lasers and so called polariton-condensates. The thresholds of these devices are identified by analysis of the emission photon number statistics and a transition from thermal light towards coherent emission is evidenced. Also, unexpected features like antibunching from a quantum dot ensemble or scattering between the condensate ground state and its excitation spectrum are discussed.
Subject Headings: Quantum optics
Semiconductor light sources
Optical coherence
Polariton condensate
Issue Date: 2011-01-21
Appears in Collections:Experimentelle Physik II

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