Quiet cascade: measuring QCL intrinsic linewidth
Authors: Bartalini S., Borri S., Cancio P., Castrillo A., Galli I., Giusfredi G., Mazzotti D., Gianfrani L., De Natale P.
Autors Affiliation: Istituto Nazionale di Ottica (INO) – CNR
European Laboratory for Non-linear Spectroscopy (LENS)
Dipartimento di Scienze Ambientali, Seconda Università di Napoli
Abstract: Researchers demonstrated direct evidence of an intrinsic linewidth of a few hundred hertz for these sources through their investigation of the frequency-noise spectral density of a free-running mid-infrared (IR) quantum-cascade laser (QCL). The researchers measured a QCL intrinsic linewidth, using the latest instrumentation with significant low noise. They tuned a 4.33-µm-emitting QCL half-way down a carbon dioxide absorption peak to test the prediction. The demonstration that QCLs have peculiar noise features provided experimental evidence of a linewidth narrowing beyond the limit set by the spontaneous emission rate. These measurements led to a better understanding of QCLs and to improved designs of their quantum-well structure.
Journal/Review: OPTICS AND PHOTONICS NEWS
Volume: 21 (12) Pages from: 32 to: 32
KeyWords: quantum cascade laserDOI: 10.1364/OPN.21.12.000032