Ultrasensitive Strain Sensor Based on V-Groove Structure Long-Period Fiber Grating

We propose and experimentally demonstrate an ultrasensitive strain sensor based on a V-groove structure long-period fiber grating (V-LPFG). The V-LPFG is fabricated by using CO2 laser to etch periodic V-groove structures on a standard single-mode fiber. Utilizing the periodic V-grooves, effectively enhancing the strain sensitivity of LPFG. The effect of different V-groove depths on the strain sensitivity of V-LPFG are discussed. The experiment results show that the sensitivity of strain is up to -229.1 pm/mu epsilon. In addition, the temperature response of the sensor is measured and the temperature sensitivity is 80.18 pm/degrees C. Its temperature-strain cross-sensitivity is as low as -0.35 mu epsilon/degrees C. The proposed ultrasensitive strain sensor has the good potential applications in engineering health monitoring and precision measurement due to its low cost, small size, simple fabrication, and high sensitivity.