Abstract
We demonstrated a high-speed mid-infrared frequency modulation spectroscopy scheme based on a distributed-feedback quantum Cascade laser for the application in trace gas sensing by means of all-optical frequency modulation. With this method, the modulation frequency spectrum of a gas sample can be obtained within the mid-infrared pulse duration of $\sim 200$ ns. A frequency modulation of the middle infrared lasing optical frequency was achieved in quantum Cascade laser with a modulation frequency of 200 MHz by illuminating with a 1550-nm near-infrared laser. For CO gas, with 2-mW near-infrared illumination, the noise-equivalent sensitivity of the frequency modulation spectroscopy was estimated to be 0.12 ppmv for an absorption length of 6.1 m, indicating an improvement by a factor of 7 compared with Voigt-fitted direct absorption spectroscopy (0.84 ppmv). The frequency modulation signal was found to be proportional to the incident near-infrared power, and therefore, the noise-equivalent sensitivity is expected to be further improved by increasing the near-infrared illumination power. This high-speed frequency modulation spectroscopy based on the distributed-feedback quantum Cascade laser has promising applications in high-speed and high-sensitivity gas sensing.
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.
