Atmospheric N2O gas detection based on an inter-band cascade laser around 3.939 μm

• 来源期刊: 中国物理B（英文版）
• 关键词: wavelength modulation spectroscopy inter-band cascade laser frequency locking nitrous oxide (N2O)
• 年，卷（期）: 2020,（1）
• 页码范围: 223-229
• 页数: 7页
• 语种: 英文
• DOI: 10.1088/1674-1056/ab5ef6

摘要

N2O is a significant atmospheric greenhouse gas that contributes to global warming and climate change. In this work, the high sensitivity detection of atmospheric N2O is achieved using wavelength modulation spectroscopy (WMS) with an inter-band cascade laser operating around 3.939 μm. A LabVIEW-based software signal generator and software lock-in amplifiers are designed to simplify the system. In order to eliminate the interference from water vapor, the detection was performed at a pressure of 0.1 atm (1 atm=1.01325×105 Pa) and a drying tube was added to the system. To improve the system performance for long term detection, a novel frequency locking method and 2 f/1 f calibration-free method were employed to lock the laser frequency and calibrate the power fluctuations, respectively. The Allan deviation analysis of the results indicates a detection limit of～20 ppb (1 ppb=1.81205 μg/m3) for a 1 s integration time, and the optimal detection limit is～5 ppb for a 40-s integration time.