High sensitivity fiber cladding SPR strain sensor based on V-groove structure

Abstract

How to couple the light in the fiber core to the cladding is an urgent issue that need to be done for the fabrication of the fiber-cladding SPR sensor, and there is no report about the fiber SPR strain sensor. Hereby, we propose and demonstrate a high sensitivity fiber cladding SPR strain sensor based on V-groove structure. By CO2 laser, the V-groove is fabricated on the single-mode fiber, and the light in the fiber core is effectively coupled to the cladding. The cladding 2cm behind the V-groove is coated with sensing gold film, and a multimode fiber is spliced with the sensing probe to construct the novel fiber cladding SPR sensor. On the basis of the investigation of the effects of different V-groove depth, number and period on the performance of fiber SPR refractive index sensor, a high sensitivity strain SPR sensor is designed and fabricated by employing the characteristic that the V-groove will deform with strain. The testing results indicate that the average refractive index sensitivity of the sensor is 2896.4nm/RIU, and the strain wavelength sensitivity is 25.92pm/µε which is much higher than that of the fiber interference and grating strain sensors, and the strain light intensity sensitivity is -4.4×10−4 a.u./µε. The proposed fiber cladding SPR strain sensor has the advantages of simple structure and convenient manufacture, and can be used for working in a narrow space.

Temperature-Compensated Multi-Point Strain Sensing Based on Cascaded FBG and Optical FMCW Interferometry

“…For example, fiber grating combined with the lever principle to achieve micro-strain measurement [ 9 ], a long-gauge fiber Bragg grating (FBG) strain sensor with enhanced strain sensitivity [ 10 ], or a silver-coated, 45-degree-radiated tilted fiber used for strain sensing [ 11 ], using three-dimensional (3D) printing technology to embed the FBG into a thermoplastic polyurethane filament can be effective in strain measurement [ 12 ], etc. The third type is the optical fiber surface plasmon resonance (SPR) strain sensor [ 13 , 14 , 15 , 16 ], which mainly makes the transmission light with total reflection at the fiber core and cladding interface contact with the metal film. However, the processing of this sensor is very difficult, and its repeatability is low.…”