Satyanarayanan S

Dual-wavelength, broadband photoacoustic technique is demonstrated for measurement of multiple gas species using a supercontinuum laser source. H2O vapor and CO2 measurements are demonstrated near 1920 and 2000 nm.

Supercontinuum laser-based broadband photoacoustic technique is demostrated for sensing CO, CO2 and H2O around 2µm. The detection limit of 6 ppm, 736 ppm and 20 ppb respectively, is attained with SNR of 3 dB.

Supercontinuum laser-based broadband photoacoustic technique is demostrated for sensing CO, CO2 and H2O around 2 μm. The detection limit of 6 ppm, 736 ppm and 20 ppb respectively, is attained with SNR of 3 dB.

This article presents a dual-wavelength band broadband photoacoustic spectroscopy (BPAS) technique ideally suited to low-energy broadband sources for industrial and environmental multigas sensing applications. The broad spectral range of the supercontinuum source is used to cover a wide range of absorption bands of various gases. The major limitation in most of the gas sensors with broadband sources is the effect of interference between gases. This article proposes a dual-wavelength technique to eliminate the impact of cross sensitivity among gases. This sensor exhibits a comprehensive concentration measurement from parts per million (ppm) to % levels. The proposed technique showed a ±1.2% error between the calculated and calibrated concentration values. We achieved a minimum detection limit (MDL) of 0.4 and 0.7 ppm for methane (CH4) with an integration time of 142 and 200 s using 2315- and 1650-nm band, respectively, 0.3 and 1.8 ppm of ammonia (NH3) with an integration time of 100 and 48 s using 2315- and 2017-nm band, respectively, and also 2.6 ppm of carbon monoxide (CO) with an integration time of 71 s using the 2315-nm band.

Hollow-core fiber and photoacoustic spectroscopy techniques are demonstrated for the measurement of atmospheric CO2 using a broadband supercontinuum laser at 2 µm wavelength range. The CO2 concentration was measured during the day and night time, was found to be around 420 ppm and 450 ppm respectively.

Hollow-core fiber b ased d etection o f C H4 a nd N H3 i s d emonstrated u sing a broadband supercontinuum laser source. The system provided a minimum detection limit of 0.49 % and 0.22 % for CH4 and NH3 in 1.6 µm and 2µm wavelength ranges, respectively.