Investigation on Strain Sensor Based on Wide V-Shaped Long Period Fiber Gratings

In this letter, a new-type of wide V-shaped long period fiber grating (WVS-LPFG) has been proposed and investigated. By employing CO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> laser polishing method, periodical V-shaped grooves are achieved on a single mode fiber (SMF). This special structure results in a high strain sensitivity up to 29.94 pm/µε at the range of 0–500 µε. Meanwhile, the temperature sensitivity of WVS-LPFG is 30.0 pm/°C in dynamic range of 20-120°C. The crosstalk between strain and temperature is 1 µε/°C, which displays diminutive influence on strain sensing. Experimental process indicates that the strain sensitivity decreases as the number of periods increasing. Additionally, the proposed strain sensor has advantages of wide range, simple structure, high sensitivity and compact size, which provides a fresh approach to solve strain sensing in harsh conditions.