Development of super luminescent diode based sensing technique for multiple-gas monitoring

All Single-Mode-Fiber Supercontinuum Source Setup for Monitoring of Multiple Gases Applications

“…Many of these setups are based on a spectroscopic absorption principle since atoms absorb light at specific wavelengths [9]. There are different techniques that are based on this principle and are used for gas monitoring and sensing such as: Tunable Diode-Laser Absorption Spectroscopy (TDLAS) [10][11][12][13][14][15][16][17][18], Tunable Laser Absorption Spectroscopy (TLAS) [19][20][21], Cavity Ring-Down Spectroscopy (CRDS) [19,22,23], Cavity Enhanced Absorption Spectroscopy (CEAS) [24], Fiber Laser Intracavity Absorption Spectroscopy (FLICAS) [25,26], gas cell with coreless fiber optic [27,28], or measurement of the incident and transmitted intensity of light travelling through a medium [29,30]. Some of these techniques use laser diodes, lasers, or tunable lasers for their high output power, narrow wavelength, and high resolution, however the poor stability of these parameters and the narrow measurable bandwidth limit the applicability of devices based on these techniques since they are tuned to detect and measure only certain absorption peaks of the molecule.…”

“…Some of these techniques use laser diodes, lasers, or tunable lasers for their high output power, narrow wavelength, and high resolution, however the poor stability of these parameters and the narrow measurable bandwidth limit the applicability of devices based on these techniques since they are tuned to detect and measure only certain absorption peaks of the molecule. Therefore, broad spectrum sources, such as those reported using Amplified Spontaneous Emission (ASE) sources [25,26,[31][32][33], Super-luminescent Diodes (SLD) [29,30,34,35], Xenon arc lamps [36,37], and supercontinuum (SC) sources [34,35,[38][39][40][41][42][43][44][45][46][47][48][49], are alternative sources that can be used to detect and measure the concentration of a pure gas or mixtures of gases. SC sources are built using a fiber laser pump and fiber optic [46] and are particularly useful given their wide bandwidth and output power when compared to ASE and SLD sources [34].…”

Off-Resonance Photoacoustic Spectroscopy Technique for Multi-Gas Sensing in Biogas Plants

“…Salazar et al have used multiple tunable diode lasers for monitoring CH 4 , CO 2 , H 2 O, and CO in a biomass gasifier . Absorption spectroscopy techniques, with broadband light sources like supercontinuum lasers and superluminescent diodes (SLED) in the near-infrared (NIR) region, have been reported for measurement of various gases, such as CH 4 , CO 2 , NH 3 , and C 2 H 2 . − However, such absorption-based measurement techniques require a long-pass gas cell for trace gas measurements. Further, in applications where a scattering medium is present such as aerosol particles, the transmitted light also experiences extinction due to scattering, which will also reduce the signal-to-noise ratio.…”