Fiber-Coupled Ozone Sensor Based on Tuning Fork-Enhanced Interferometric Photoacoustic Spectroscopy

In this paper, a completely fiber-coupled ozone sensor based on tuning fork (TF)-enhanced photoacoustic spectroscopy is presented. Crystalline silicon micro-TFs are processed and characterized. Their photoacoustically induced motion is monitored by a compact intensity interferometer. An acoustic microresonator for this new type of TFs is optimized. A frequency-doubled Nd:YAG laser is used as an excitation source. The sensor performance is assessed by calibration measurements. It reaches a detection limit of S = 2.13 ppm ± 0.02 ppm and a noise-equivalent absorption sensitivity of D = (1.27 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-9</sup> ± 1.2 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-11</sup> ) cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> W(Hz) <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1/2</sup> .