High-sensitivity strain sensor implemented by hybrid cascaded interferometers and the Vernier-effect
Abstract
A strain sensor implemented by cascading a Sagnac interferometer (SI) and a fiber modal interferometer (FMI) was proposed and experimentally demonstrated. The SI serving as the fixed part comprises a length of polarization maintaining fiber (PMF), and the FMI serving as the sliding part comprises single mode fiber (SMF) and a length of few mode fiber (FMF) with core-offset structure. By closing the free spectral ranges (FSRs) of the SI and FMI, Vernier-effect exists and makes contribution to magnify the sensitivity. Through monitoring the FSR of the spectral envelope, the strain sensing is realized. A high sensitivity of 65.71 pm/μɛ which is more than 20 times higher than that of the single FMI is obtained experimentally. Moreover, thanks to the polarization insensitivity of FMF, the proposed sensor is immune to environmental disturbance and suitable for physical sensing applications.
- Publication:
-
Optics Laser Technology
- Pub Date:
- November 2019
- DOI:
- 10.1016/j.optlastec.2019.105591
- Bibcode:
- 2019OptLT.11905591L
- Keywords:
-
- Fiber optics sensors;
- Polarization maintaining fiber;
- Few mode fiber;
- Vernier-effect