Near-IR telecommunication diode laser based double-pass QEPAS sensor for atmospheric CO₂detection

Abstract

A novel double pass quartz enhanced photoacoustic spectroscopy (QEPAS) sensor for atmospheric CO 2 detection is developed by use of a 1.5 μm telecommunication diode laser. A low-cost high-reflection concave mirror is positioned behind a traditional QEPAS based acoustic detection module to enhance the absorption optical path and improve the detection sensitivity. The obtained minimum detection limit is 29 ppmV for 1 s averaging time which corresponds to a normalized noise equivalent absorption coefficient (NNEA, 1σ) . With a 247 s averaging time, it demonstrates an ultimate detectable sensitivity of 1.74 ppmV.

Acoustic Detection Module Design of a Quartz-Enhanced Photoacoustic Sensor

“…Such a high gas tightness can be realized by means of a vacuum KF interface. With slow relaxation molecules, such as nitric oxide (NO), carbon dioxide (CO 2 ) and carbon monoxide (CO), the optimal pressure is ~ atmospheric pressure [ 5 , 31 , 32 , 33 ]. A traditional O-ring seal is sufficient in order to implement gas tightness of the ADM.…”

“…A detection limit of 0.65 ppmv and a normalized noise equivalent absorption coefficient ( NNEA ) of 7.2 × 10 −9 cm −1 W/ was achieved. So far, the QEPAS sensor with this ADM has been employed to detect several gases in the visible spectral region (e.g., NO 2 ) [ 36 , 37 ], in the NIR spectral range (e.g., NH 3 , CO 2 , CO, HCN, HCl, H 2 O, H 2 S, CH 4 , C 2 H 2 , C 2 H 4 ) [ 5 , 30 , 32 , 33 , 38 , 39 , 40 , 41 , 42 , 43 ] and in the MIR spectral region (e.g., NO, N 2 O, CO, NH 3 , C 2 H 6 , (CH 3 ) 2 CO and CH 2 O) [ 31 , 44 , 45 , 46 , 47 , 48 ]. Moreover, this ADM was also used in the development of the QEPAS technique, including the optimization of an on-beam QEPAS spectrophone [ 29 ], the application of an off-beam spectrophone [ 41 ], the realization of a double on-beam QEPAS spectrophone [ 49 ] and the position optimization of the AmR [ 34 ] and the invention of beat frequency QEPAS for fast and calibration-free continuous trace-gas monitoring [ 50 ].…”

Application of Micro Quartz Tuning Fork in Trace Gas Sensing by Use of Quartz-Enhanced Photoacoustic Spectroscopy

“…The 9/125 single mode fiber was terminated with an angled FC/APC connector. The beam quality was shown in our previous publication [38]. A custom control electronic unit (CEU) [20] was employed as the laser driver to control the temperature and injection current of the diode laser.…”

Impact of Humidity on Quartz-Enhanced Photoacoustic Spectroscopy Based CO Detection Using a Near-IR Telecommunication Diode Laser

“…Near-IR telecommunication diode lasers have been widely used in spectroscopic technology due to their narrow line-width, fast tuning rate, stable emitting wavelength, and long life [ 18 , 19 , 20 ]. Moreover, compared with the mid-infrared quantum cascade lasers (QCLs) or far-infrared Terahertz (THz) lasers [ 21 , 22 , 23 ], near-IR telecommunication lasers are more cost-effective.…”