High-sensitivity fiber SPR strain sensor based on n-type structure.

At present, fiber strain sensors are mainly of the grating type and interference type, while there is relatively little research on fiber surface plasmon resonance (SPR) strain sensors. In this Letter, we propose a highly sensitive fiber SPR strain sensor based on an n-type structure. The strain changes the shape of the fiber n-type structure, causing the transmission mode of light in the fiber to change, thereby changing the SPR incidence angle and causing the SPR resonance valley wavelength to shift, achieving highly sensitive SPR strain sensing. The test results indicate that the strain sensing sensitivity of the proposed sensor reaches 21.33 pm/µε, and two n-type structures are connected in series to obtain a double n-type structure, further enhancing the strain sensing sensitivity to 33.44 pm/µε. This fiber strain sensor has advantages of high sensitivity, low temperature cross talk, strong structural stability, and low production cost, and is expected to become a new solution for wearable intelligent monitoring equipment and strain sensors in the aerospace field.