An Improved Strain Sensor Based on Long-Period Fiber Grating With a Local Ellipse-Core Structure

In this paper, we proposed a novel long-period fiber grating strain sensor based on local ellipse-core fiber (LEC-LPFG). The LEC-LPFG was fabricated by laser polishing and local heating methods, which could efficiently transform a single-mode fiber (SMF) into a periodic ellipse-core fiber. The effects associated with the fiber elliptical core shape were shown to significantly influence the strain sensitivity of the LEC-LPFG. Further, it was demonstrated that the LEC-LPFG has a high strain sensitivity of −20.2 pm/
$\mu \varepsilon $
and a temperature sensitivity of 68.6 pm/°C. Our work provides a new technology for straightforward, low-cost, and large-scale productions of premium fiber optical strain sensors which are desirable in many practical applications.