Abstract
The concept of a multi-wavelength quantum cascade laser emitting at two or more spectrally well-separated wavelengths is highly appealing for applied spectroscopy, as it allows detecting several species with compact and cost-efficient optical setups. Here we present a practical realization of such a dual-wavelength setup, which is based on a room-temperature quantum cascade laser emitting single-mode at 1600 cm-1 and 1900 cm-1 and is thus well-suited for simultaneous NO and NO2 detection. Operated in a time-division multiplexed mode, our spectrometer reaches detection limits of 0.5 and 1.5 ppb for NO2 and NO, respectively. The performance of the system is validated against the well-established chemiluminescence detection while measuring the NOx emissions on an automotive test-bench, as well as upon monitoring the pollution at a suburban site.
Highlights
The excellent sensitivity, specificity and speed of state-of-the-art mid-infrared spectrometers based on single-mode quantum cascade (QC) [1,2,3] or interband cascade (IC) [4, 5] lasers has secured their leading position for trace gas detection in environmental sciences [6,7,8], medical diagnosis [9,10,11], and industrial process control [12]
The concept of a multi-wavelength quantum cascade laser emitting at two or more spectrally well-separated wavelengths is highly appealing for applied spectroscopy, as it allows detecting several species with compact and cost-efficient optical setups
We present a practical realization of such a dual-wavelength setup, which is based on a roomtemperature quantum cascade laser emitting single-mode at 1600 cm−1 and 1900 cm−1 and is well-suited for simultaneous NO and NO2 detection
Summary
The excellent sensitivity, specificity and speed of state-of-the-art mid-infrared spectrometers based on single-mode quantum cascade (QC) [1,2,3] or interband cascade (IC) [4, 5] lasers has secured their leading position for trace gas detection in environmental sciences [6,7,8], medical diagnosis [9,10,11], and industrial process control [12]. Commercial implementations of multi-compound spectrometers rely on multiple DFB laser modules, each selected for a given target gas, whose outputs are combined into a single multi-wavelength beam using macroscopic optical elements, such as beam splitters or dichroics [18], dispersive elements [19] or metallic reflectors [12] In this way, for instance, up to four QC lasers were combined through a four-face pyramidal mirror to measure five different components of cigarette smoke [18], and highly time-resolved molecular plasma diagnostics was accomplished using three lasers coupled by a series of four off axis parabolic mirrors [12]. Since both frequencies are generated in the same optical waveguide, their emission directions are strictly identical, providing for multi-species detection without the need for multiple laser modules or beam combining optics
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
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.
