Ultrastable Laser Wavelength Locking Technique Optimized for WMS-Based Methane Detection

Cheng, Yaopeng; Wang, Fupeng; Wu, Jinghua; Liang, Rui; Wang, Qiang; Wei, Yubin; Sun, Jiachen; Li, Qian; Xue, Qingsheng

doi:10.1109/jsen.2023.3246508

Cited by 3 publications

(7 citation statements)

References 49 publications

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“…Standard 2nd and 3rd harmonic curves are simulated in Figure 2, and the maximum value H 2max of 2nd harmonic signal is always measured to predict gas concentration. However, the symmetric point H 3ref of 3rd harmonic signal as labeled in Figure 2 has nothing to do with the gas concentration and laser power fluctuations, which has been employed as a reference to locate the absorption center λ 0 for wavelength locking in many studies [21][22][23][24][25]. The monotonic region near H 3ref is utilized as the input of PID controller to dynamically stabilize the laser wavelength at λ 0 .…”

Section: Methodology Demonstrationmentioning

confidence: 99%

“…R set is a high-precision rheostat with a low-temperature drift of 50 ppm/ • C to guarantee the precision of V set . C 1 , C 2 , C 3 , R 3 , R 4 , R 5 are key parameters of the PID controller, which are chosen based on our experience reported in a previous study [25]. L 1 , L 2 , C 4 , R 5 constitute the basic LC filter to rectify the TEC driving current from MOS gates.…”

Section: Experiments Verification 31 Ultra-stable Temperature Control...mentioning

confidence: 99%

“…In the following step, the performance of the temperature controller is tested in advance when it operates in the standard mode (the SPDT switch is turned to position a in Figure 4). A butterfly-packaged DFB laser [25] is chosen as the object for temperature control. In the very beginning, as shown in Figure 6a,b, the temperature controller is not activated, the voltage of the thermistor inside the DFB laser is recorded for a while and the corresponding temperature is calculated.…”

Section: μHmentioning

confidence: 99%

“…Zhang et al [24] reported a 2.004 µm DFB laser locked with a frequency deviation of 6 MHz over 10 min for CO 2 measurement. Recently, Cheng et al [25] demonstrated a DFB laser locked at 1653.72 nm with a fluctuation of less than 406 kHz by virtue of optimized PID parameters and successfully applied it for CH 4 detection. Compared with the PDH method, the odd harmonic-based wavelength locking technique is already simplified so much.…”

Section: Introductionmentioning

confidence: 99%

“…In this study, we develop a temperature controller based on a commercial chip MAX1978 and successfully improve the temperature stability to an ultra-high level of 0.5 m • C. To our knowledge, this is almost the best temperature-controlling result reported so far. Considering that the wavelength response towards the temperature of the CH 4 laser diode used in our lab is 100 pm/ • C [25], the laser wavelength can be potentially stabilized at 1653.72 nm with a fluctuation of 5.5 MHz (0.05 pm), ideally. Therefore, the second part of this study is proposing a strategy to introduce a feedback signal to the temperature controller to stabilize the laser wavelength dynamically.…”

Section: Introductionmentioning

confidence: 99%

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Ultra-Stable Temperature Controller-Based Laser Wavelength Locking for Improvement in WMS Methane Detection

Wang

Liang

et al. 2023

Sensors

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In the wavelength modulation spectroscopy (WMS) gas detection system, the laser diode is usually stabilized at a constant temperature and driven by current injection. So, a high-precision temperature controller is indispensable in every WMS system. To eliminate wavelength drift influence and improve detection sensitivity and response speed, laser wavelength sometimes needs to be locked at the gas absorption center. In this study, we develop a temperature controller to an ultra-high stability level of 0.0005 °C, based on which a new laser wavelength locking strategy is proposed to successfully lock the laser wavelength at a CH4 absorption center of 1653.72 nm with a fluctuation of fewer than 19.7 MHz. For 500 ppm CH4 sample detection, the 1σ SNR is increased from 71.2 dB to 80.5 dB and the peak-to-peak uncertainty is improved from 1.95 ppm down to 0.17 ppm with the help of a locked laser wavelength. In addition, the wavelength-locked WMS also has the absolute advantage of fast response over a conventional wavelength-scanned WMS system.

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