Abstract:We propose and demonstrate a pressure sensor based on a micro air bubble at the end facet of a single mode fiber fusion spliced with a silica tube. When immersed into the liquid such as water, the air bubble essentially acts as a Fabry-Pérot interferometer cavity. Such a cavity can be compressed by the environmental pressure and the sensitivity obtained is >1000 nm/kPa, at least one order of magnitude higher than that of the diaphragm-based fiber-tip sensors reported so far. The compressible FabryPérot interferometer cavity developed is expected to have potential applications in highly sensitive pressure and/or acoustic sensing. 447-449 (2005). 13. D. Donlagic and E. Cibula, "All-fiber high-sensitivity pressure sensor with SiO 2 diaphragm," Opt. Lett. 30(16), 2071-2073 (2005). 14. X. Wang, J. Xu, Y. Zhu, K. L. Cooper, and A. Wang, "All-fused-silica miniature optical fiber tip pressure sensor," Opt. Lett. 31(7), 885-887 (2006). 15. W. Wang, N. Wu, Y. Tian, C. Niezrecki, and X. Wang, "Miniature all-silica optical fiber pressure sensor with an ultrathin uniform diaphragm," Opt. Express 18(9), 9006-9014 (2010). 16. E. Cibula, S. Pevec, B. Lenardič, É. Pinet, and D. Donlagic, "Miniature all-glass robust pressure sensor," Opt.Express 17(7), 5098-5106 (2009