Highly sensitive photoacoustic gas sensor with micro-embedded acoustic resonator for gas leakage detection

In this work, a photoacoustic (PA) gas sensor with a microembedded acoustic resonator for gas leakage detection was demonstrated. The micro-embedded acoustic resonator was fabricated by putting a leaky hollow-core fiber (L-HCF) into a cylindrical buffer chamber. The L-HCF was utilized as the PA cavity and the light transmission media simultaneously. The optimal inner diameter of the L-HCF was 1.7 mm. The embedded acoustic resonator was experimentally proven to be equivalent to a T-type half-open acoustic resonator, but the structure became much more compact. The volume of the amount of gas in the cell was only similar to 0.3 mL, and the gas diffusion time to fill the sensor under room temperature (25 degrees C) and ambient pressure (101 kPa) was similar to 44 s. Trace acetylene (C2H2) in pure nitrogen (N-2) was chosen as the target gas, and the minimum detectable limit (MDL) reached 29 ppb when the lock-in integration time was 1 s. The normalized noise equivalent absorption (NNEA) coefficient was calculated to be 3.0x10(-9) W center dot cm(-1) center dot Hz(-1/2). The micro-resonant PA gas sensor, with merits of compactness, lowgas consumption, and low cost, has the potential to be a remote gas sensing scheme in fields of environmental protection, industrial process monitoring, and so on. (c) 2023 Optica Publishing Group