A Fabry-Perot interferometer based on probe-embedded bubble for ultrasensitive strain measurement

A high-sensitivity Fabry-Perot interferometer (FPI) strain sensor based on tapered single-mode fiber (SMF) probe embedded in microbubble is proposed and verified. The two reflective surfaces of this FPI are composed of the two tapered SMF ends and assembled within a bubble. The distance between the reflection face can be flexibly adjusted to enhance the strain sensitivity of the sensor. Experimental result shows that the strain sensitivity of proposed FPI sensor reaches to 142.2 pm/με. Meanwhile, the sensor demonstrates low temperature sensitivity of 2.19 pm/°C, which achieves an extremely low temperature-strain crosstalk of less than 16.6 nε/°C. Moreover, the proposed FPI sensor possesses advantages of high sensitivity, low-cost and compact length, which shows potential in areas of micro strain measurement.