All-Fiber Strain Sensor Based on Dual Side V-Grooved Long-Period Fiber Grating

We propose and experimentally demonstrate an all-fiber strain sensor based on dual side V-grooved long-period fiber grating (DSV-LPFG). This fiber structure is achieved by polishing a series of asymmetrical V-shaped grooves on a single mode fiber (SMF), which is fabricated by a high-frequency CO
₂
laser. The asymmetrically periodic structure enhances the sensitivity of strain and shortens the total length of fiber grating. Experimental results show that the strain sensitivity of the structure reaches 44.6 pm/
$\mu \varepsilon $
in the dynamic range of 0-
$1000~\mu \varepsilon $
. Meanwhile, the strain sensitivity of the sensor with the different periodic numbers and the offset distance are investigated. Temperature sensitivity of 53 pm/°C is obtained, which exhibits a small temperature cross-sensitivity of
$1.18~\mu \varepsilon /^{\circ }\text{C}$
. Furthermore, the proposed strain sensor exhibits the advantages of simple structure, convenient fabrication and low cost.