Measurement of Atmospheric Dimethyl Sulfide with a Distributed Feedback Interband Cascade Laser

Abstract

This paper presents a mid-infrared dimethyl sulfide (CH3SCH3, DMS) sensor based on tunable laser absorption spectroscopy with a distributed feedback interband cascade laser to measure DMS in the atmosphere. Different from previous work, in which only DMS was tested and under pure nitrogen conditions, we measured DMS mixed by common air to establish the actual atmospheric measurement environment. Moreover, we used tunable laser absorption spectroscopy with spectral fitting to enable multi-species (i.e., DMS, CH4, and H2O) measurement simultaneously. Meanwhile, we used empirical mode decomposition and greatly reduced the interference of optical fringes and noise. The sensor performances were evaluated with atmospheric mixture in laboratory conditions. The sensor’s measurement uncertainties of DMS, CH4, and H2O were as low as 80 ppb, 20 ppb, and 0.01% with an integration time 1 s, respectively. The sensor possessed a very low detection limit of 9.6 ppb with an integration time of 164 s for DMS, corresponding to an absorbance of 7.4 × 10−6, which showed a good anti-interference ability and stable performance after optical interference removal. We demonstrated that the sensor can be used for DMS measurement, as well as multi-species atmospheric measurements of DMS, H2O, and CH4 simultaneously.

Mid-Infrared Tunable Laser-Based Broadband Fingerprint Absorption Spectroscopy for Trace Gas Sensing: A Review

“…All these components with higher R can be added together to reconstruct a WMS-2f free from the interference of fringes and noise. Generally, this method can improve the sensor sensitivity by about 30% [164].…”

“…Multicomponent spectral fitting is mainly used to eliminate spectral interference, which commonly occurs in MIR detection. Furthermore, benefitting from the use of multivariate regression and nonlinear least square fitting, it can calculate the multi-component concentration in a gas mixture, i.e., achieving multiple component detection simultaneously using a single DFB ICL [164,165]. The Levenberg-Marquardt (LM) algorithm, also known as the damped least-squares method, was applied for the data fitting.…”

Quantitative Determination of Loss Properties of Semiconductor Laser Beams Propagating in Hollow Waveguides

“…Many studies have focused on theoretical models for light transmission in metallic and dielectric waveguides, and have provided explanations of laser modes and energy loss on average [22], [23]. Recently, much attention has been paid to HWG-based compact sensors combined with quantum cascade lasers (QCLs) or interband cascade lasers (ICLs) [24]- [26]. These lasers present distinctive features of single-mode, Gaussian beams and high angular spread [27]- [29], which lead to different propagation properties in HWGs.…”

Compact Hollow Waveguide Mid-Infrared Gas Sensor For Simultaneous Measurements of Ambient CO2 and Water Vapor

“…The HWG was first proposed by Garmire et al [9] in 1976. It has been continuously evolved and spread to numerous applications [10][11][12][13][14][15][16][17], and is generally defined as a capillary tube whose core is air and surrounding has a refractive index higher than 1.0. In order to reduce the light propagation loss, the HWG is usually coated with a metallic layer of Ag on the inner wall of the silica glass tubing [18] and then a dielectric layer of AgI over the metal film [19].…”