A compact fiber-based sensor for wide range strain measurement

•The proposed strain sensor has a wide measurable range of 0–6800 με and linear response of 5.4 pm/με.•The structure is compact with only 4 mm and has a low manufacturing cost.•The strain sensitivity and measurable range of J-LPFG are inversely proportional to the number of periods, which is proved by simulation and experimental results. In this paper, a compact strain sensor for wide range measurement is proposed and experimentally investigated. The proposed sensor is configured by jagged long period fiber grating (J-LPFG), which is fabricated by etching on two opposite sides of single mode fiber (SMF). Since the appearance of the structure seems like jag, we name it by J-LPFG. This unique physical shape brings itself a wide measurable range and linear strain response. Meanwhile, we compare the strain sensitivities of J-LPFGs with different periods through experiments. As the consequence of experiments, J-LPFG with 8 periods exhibits the best strain response which reaches 5.4 pm/με within the dynamic range of 0–6800 με. Furthermore, the strain sensitivity and measurable range of J-LPFG decrease as the number of periods increases. This theory is verified by experiments and strain distribution simulation. In addition, the temperature sensitivity of 8-periods J-LPFG is 57 pm/°C in the range of 30–150 °C. Due to low cost, simple preparation process, and wide measurable range, J-LPFG has great potential to be applied in practical engineering.