A new strain sensor based on depth-modulated long-period fiber grating

Abstract In this paper, a novel strain sensor based on Depth-Modulated Long Period Fiber Grating (DM-LPFG) is presented and demonstrated. One side polished deformations with different milling depth are fabricated by a high frequency CO2 laser, so the DM-LPFG possesses a staircase-shaped structure. This kind of structure provides the high strain sensitivity of DM-LPFG. Experimental results clearly demonstrate that the structure has excellent mechanical capacity and repeatability. The sensor has a considerable strain sensitivity, which can reach up to 27.4 pm/μe with the range of 0-450 μe, it is an order of magnitude higher than conventional CO2 laser induced LPFG. The temperature characteristic is 49 pm/℃ with the range of 30-170 ℃. Furthermore, the strain sensor possesses a compact structure, with a total length of 9 mm.