Miniature optical fiber photoacoustic gas sensor based on a 3D microprinted ferrule-top optomechanical resonator

We present a small-size high-sensitivity optical fiber photoacoustic gas sensor based on a sub-millimeter optomechanical resonator (OMR) that is directly 3D micro-printed on the end-face of a fiber-optic ferrule. The 3D micro-printed OMR and the end-face of the optical fiber form a low-finesse Fabry-Pérot (FP) microcavity for interferometric acoustic detection, achieving an acoustic sensitivity of 296 mV/Pa. Together with a pump laser beam, an optical fiber OMR-based photoacoustic gas sensor is demonstrated to detect acetylene gas at the concentration level of 137 parts per billion. This highly sensitive and compact optical fiber gas sensor offers a promising solution for trace-gas detection in diverse applications ranging from biomedical diagnostics to in-reactor monitoring.