Enhanced near-infrared QEPAS sensor for sub-ppm level H2S detection by means of a fiber amplified 1582 nm DFB laser

Abstract

Enhanced near-infrared QEPAS sensor for sub-ppm level H 2 S detection by means of a fiber amplified 1582<ce:hsp sp=0.25/>nm DFB laser, Sensors and Actuators B: Chemical (2015), http://dx. Abstract:A power-boosted quartz-enhanced photoacoustic spectroscopy (QEPAS) sensor is developed for sub-ppm H 2 S trace-gas detection in the near-infrared spectral region. The sensor is based on off-beam QEPAS with an erbium-doped fiber amplified 1582 nm distributed feedback (DFB) laser. The offset of the sensor floor noise caused by stray light and gas flow can be removed by an electrical modulation cancellation method, which lowers the noise to the theoretical thermal noise level. The sensor was optimized in terms of gas pressure and current modulation A c c e p t e d M a n u s c r i p 2 depth for H 2 S detection at 6320.6 cm -1 . The linearity of the sensor response to the laser power and H 2 S concentration confirms that saturation does not occur. With ~ 1.4 W optical excitation power and 67 sec averaging time, a H 2 S detection sensitivity of 142 ppbv (parts per billion by volume) is achieved at atmospheric pressure and room temperature, which is the best value, reported in the literature so far for H 2 S QEPAS sensors. A side-by-side sensitivity comparison for different sensor systems is also reported.

Review of Recent Advances in QEPAS-Based Trace Gas Sensing

“…Recently, a QEPAS sensor system based on an EDFA-amplified diode laser was successfully used in acetylene (C 2 H 2 ), hydrogen sulfide (H 2 S), and ammonia (NH 3 ) detection [52][53][54]. In [52], a near-infrared, continuous-wave diode laser with emitting power of 6.7 mW served as the seed laser.…”

Quartz Enhanced Photoacoustic Detection Based on an Elliptical Laser Beam

“…Quartz-enhanced photoacoustic spectroscopy (QEPAS), a variant of PAS, employs a low-cost and small-size quartz tuning fork (QTF) as a sharply resonant acoustic transducer to sense the weak light-induced sound wave. QEPAS has been widely used for detecting trace gas since its first demonstration in 2002 [14][15][16][17][18][19][20][21]. It combines the main merits of conventional PAS with the advantages of a standard QTF which has a high resonance frequency and narrow resonance width, providing a robust, compact and reliable spectrophone.…”

Ppb-level detection of ammonia based on QEPAS using a power amplified laser and a low resonance frequency quartz tuning fork

“…An erbium-doped fiber amplifier (EDFA) offers several advantages, such as high gain, low noise, polarization independence, and fiber compatibility [15,16]. An EDFA can be used to achieve amplification gain of more than 30 dB when an appropriate seed diode laser beam is injected and was successfully used in QEPAS based sensor systems [17,18]. Three operating wavelength bands (S band: 1450-1550 nm, C band: 1520-1570 nm, and L band: 1565-1610 nm) are commercially available.…”