Abstract
We present an experimental and theoretical study on the gain mechanism in a photonic-crystal-cavity nanolaser with embedded quantum dots. From time-resolved measurements at low excitation power we find that four excitons are coupled to the cavity. At high excitation power we observe a smooth low-threshold transition from spontaneous emission to lasing. Before lasing emission sets in, however, the excitons are observed to saturate, and the gain required for lasing originates rather from multi-excitonic transitions, which give rise to a broad emission background. We compare the experiment to a model of quantum-dot microcavity lasers and find that the number of excitons that must be included to fit the data largely exceeds the measured number, which shows that transitions involving the wetting layer can provide a surprisingly large contribution to the gain.
Highlights
Lasers can deliver coherent, narrow-band, and single-mode light and have become ubiquitous in contemporary technology
We present an experimental and theoretical study on the gain mechanism in a photonic-crystal-cavity nanolaser with embedded quantum dots
Before lasing emission sets in, the excitons are observed to saturate, and the gain required for lasing originates rather from multiexcitonic transitions, which give rise to a broad emission background
Summary
Narrow-band, and single-mode light and have become ubiquitous in contemporary technology. A stark discrepancy between atomic laser models and experiment was found [11]: lasing was observed even when the excitons were strongly detuned from the cavity This non-resonant coupling has been the subject of intense experimental [14,15,16,17,18] and theoretical [16, 19, 20] investigations and it is understood that the dominant mechanisms are phonons at small detunings [18, 21] and, at large excitation powers and/or large detunings, multi-excitonic configurations due to hybridization with the wetting-layer states [16, 17], which may be explained as Auger processes involving wetting-layer states [22]. The gain orginates from wetting-layer-mediated processes, which lead to a surprisingly high gain
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
