Vector curvature sensor based on asymmetrically polished long-period fiber grating

In this paper, we experimentally propose and theoretically investigate a two-dimensional vector curvature sensor based on asymmetrically polished long period fiber grating (AP-LPFG). This sensor is fabricated by a high-frequency CO2 laser in order to polish periodic asymmetrical V-shaped grooves on a single mode fiber (SMF). Such grooves efficiently enhances the bending sensitivity of sensor and shorten the length of the structure to 7.39 mm. Experimental results show that the sensitivity of AP-LPFG reaches 30.85 nm/m(-1) in the direction of the X-axis and 0.97 nm/m(-1) in the direction of the Y-axis. Meanwhile, the temperature response of AP-LPFG is carried out, which is 76 pm/degrees C in range of 30-160 degrees C. Moreover, the AP-LPFG has the features of compact length and simple structure, which shows the potential in curvature sensing.