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.
|Titolo:||Quiet Cascade: Measuring QCL Intrinsic Linewidth|
|Autori interni:||GIANFRANI, Livio|
|Data di pubblicazione:||2010|
|Rivista:||OPTICS & PHOTONICS NEWS|
|Appare nelle tipologie:||1.1 Articolo in rivista|