TT-type resonator-based differential photoacoustic spectroscopy for trace gas detection

A novel TT -type resonator was proposed for the first time, to our knowledge, to realize differential photoacoustic (PA) detection for trace gas measurement. The special design of the TT -type resonator allows us to install the microphone at the resonant center of the acoustic field to maximize the use of the absorption -induced PA signal. To meet the requirement of low gas consumption and easy integration, the TT -type resonator -based PA cell was fabricated as a fibercoupled module with an inner volume of only 1.1 ml. For validation, the TT -type PA cell was integrated to a photoacoustic spectroscopy (PAS) system for acetylene detection. As a result, a linearity of 0.99999 was achieved in a concentration range from 0 to 5000 ppm with a noise equivalent sensitivity of 101 ppb. The proposed TT -type resonator contributes a new style of PA cell structure to the field of PAS gas detection, combining the advantages of easy integration, low gas consumption, differential detection, and photoacoustic enhancement together. (c) 2024 Optica Publishing Group