A quantum cascade laser（QCL） based system for simultaneous detection of CO and CO_2 is developed.The QCL can scan over two neighboring CO（2055.40 cm^（-1）） and CO_2（2055.16 cm^（-1）） lines with a single curren...A quantum cascade laser（QCL） based system for simultaneous detection of CO and CO_2 is developed.The QCL can scan over two neighboring CO（2055.40 cm^（-1）） and CO_2（2055.16 cm^（-1）） lines with a single current scan.The wavelength modulation spectroscopy（ f = 20 k Hz） is utilized to enhance the signal-to-noise ratio.A white cell with an effective optical path length of 74 m is used.The calibration of the sensor is performed and minimum detection limits of 1.3 ppb（1 × 10^（-9））for CO and 0.44 ppm（1 × 10^（-6）） for CO_2 are achieved.展开更多
Electrothermal metasurfaces have garneredconsiderable attention owing to their ability to dynamicallycontrol thermal infrared radiation. Although previousstudies were mainly focused on metasurfaces with infiniteunit c...Electrothermal metasurfaces have garneredconsiderable attention owing to their ability to dynamicallycontrol thermal infrared radiation. Although previousstudies were mainly focused on metasurfaces with infiniteunit cells, in practice, the finite-size effect can be a criticaldesign factor for developing thermal metasurfaces withfast response and broad temperature uniformity. Here, westudy the thermal metasurfaces consisting of goldnanorods with a finite array size, which can achieve aresonance close to that of the infinite case with onlyseveral periods. More importantly, such a small footprintdue to the finite array size yields response time down to ananosecond level. Furthermore, the number of the unitcells in the direction perpendicular to the axis of nanorodsis found to be insensitive to the resonance and responsetime;thus, providing a tunable aspect ratio that can boostthe temperature uniformity in the sub-Kelvin level.展开更多
基金Project supported by the National Key Scientific Instrument and Equipment Development Project of China(Grnat No.2014YQ060537)the National Basic Research Program of China(Grant No.2013CB632803)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA05040102)the National Natural Science Foundation of China(Grant No.41405134)
文摘A quantum cascade laser（QCL） based system for simultaneous detection of CO and CO_2 is developed.The QCL can scan over two neighboring CO（2055.40 cm^（-1）） and CO_2（2055.16 cm^（-1）） lines with a single current scan.The wavelength modulation spectroscopy（ f = 20 k Hz） is utilized to enhance the signal-to-noise ratio.A white cell with an effective optical path length of 74 m is used.The calibration of the sensor is performed and minimum detection limits of 1.3 ppb（1 × 10^（-9））for CO and 0.44 ppm（1 × 10^（-6）） for CO_2 are achieved.
文摘Electrothermal metasurfaces have garneredconsiderable attention owing to their ability to dynamicallycontrol thermal infrared radiation. Although previousstudies were mainly focused on metasurfaces with infiniteunit cells, in practice, the finite-size effect can be a criticaldesign factor for developing thermal metasurfaces withfast response and broad temperature uniformity. Here, westudy the thermal metasurfaces consisting of goldnanorods with a finite array size, which can achieve aresonance close to that of the infinite case with onlyseveral periods. More importantly, such a small footprintdue to the finite array size yields response time down to ananosecond level. Furthermore, the number of the unitcells in the direction perpendicular to the axis of nanorodsis found to be insensitive to the resonance and responsetime;thus, providing a tunable aspect ratio that can boostthe temperature uniformity in the sub-Kelvin level.
