An ultra-sensitive gas pressure sensor based on tapered fiber coated with PDMS film working at TAP

• Ascribing to the high refractive index of PDMS, the tapered SMF covered with PDMS can work at turning around point with larger taper diameter, which effectively enhance the structural strength and stability. • The porous character of PDMS film makes the interferometer have ultrahigh gas pressure sensitivity. • By using spin-processing method, the thickness of the PDMS film covering the fiber taper can reach only the order of micron, so that the pressure recovery time of the sensor is as short as 20 s. An ultra-sensitive gas pressure sensor based on tapered single-mode fiber (SMF) coated with thin polydimethylsiloxane (PDMS) film which works at turning around point (TAP) is proposed and demonstrated. Ascribing to the high refractive index of PDMS, the tapered SMF covered with PDMS can work at TAP with larger taper diameter, which effectively enhance the structural strength and stability. At the same time, the porous character of PDMS film makes the interferometer have ultrahigh gas pressure sensitivity. By using spin-processing method, the thickness of the PDMS film covering the fiber taper can reach only the order of micron, so that the pressure recovery time of the sensor is as short as 20 s. Experimental results show that the gas pressure sensitivity of the proposed sensor can be as high as −159.80 nm/MPa in the range from 1 KPa to 100 KPa, and another dip away from the TAP obtains the sensitivity of −69.61 nm/MPa.