25 October 1999 Spectral and modulation performance of quantum cascade lasers with application to remote sensing
Author Affiliations +
Abstract
We have characterized the spectral noise density and frequency modulation performance of an 8.5 micron quantum- cascade diode (QC) laser operating continuously at liquid nitrogen temperatures. The phase noise is measured by fixing the laser frequency in the half-height region of a molecular resonance and measuring the fluctuations in absorbance; these fluctuations are then accurately converted into measurements in the fluctuations of the absolute frequency. A Fourier analysis of the intrinsic spectral/phase noise show a 1/f2 dependence up to the measurement bandwidth limit of approximately 1 MHz. The laser linewidth is < 1 MHz when measured over several milliseconds. Servo locking schemes will be discussed with the implication that QC laser sources can be stabilized to a high degree. The frequency modulation performance of a QC laser has been measured and synchronous detection of f, 2f and 3f absorption signals (nitrous oxide at 8.5 micrometers ) has been achieved with direct modulation of the injection current.
© (1999) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Richard M. Williams, James F. Kelly, Steven W. Sharpe, John S. Hartman, Claire F. Gmachl, Federico Capasso, Deborah L. Sivco, James N. Baillargeon, Alfred Y. Cho, "Spectral and modulation performance of quantum cascade lasers with application to remote sensing", Proc. SPIE 3758, Application of Tunable Diode and Other Infrared Sources for Atmospheric Studies and Industrial Processing Monitoring II, (25 October 1999); doi: 10.1117/12.366458; https://doi.org/10.1117/12.366458
PROCEEDINGS
12 PAGES


SHARE
Back to Top