Highly sensitive SPR curvature sensor based on graded-index fiber

作者：Liu, Chunbiao; Liu, Chunlan; Wei, Yong; Shi, Chen; Wang, Rui; Wang, Xingkai; Ren, Puxi; Tang, Yixiong; Liu, Zhihai; Zhang, Yu

来源：Optics Letters, 2023, 48(12): 3135-3138.

DOI：10.1364/OL.492723

At present, fiber curvature sensors based on surface plas-mon resonance (SPR) are mostly of the multimode fiber core type or cladding type. These types have many SPR modes, resulting that the sensitivity cannot be adjusted and is difficult to improve. In this Letter, a highly sensitive SPR curvature sensor based on graded-index fiber is proposed. The light-injecting fiber is eccentrically connected with the graded-index fiber to inject single-mode light. Due to the self-focusing effect, the light beam propagates in the graded -index multimode fiber with a cosine trajectory, and the cosine beam contacts the flat grooved sensing region fab-ricated on the graded-index fiber to generate SPR. Due to the single transmission mode of the proposed fiber SPR sen-sor, the curvature sensing sensitivity is greatly improved. By changing the light injection position of the graded-index multimode fiber, the sensitivity can be adjusted. The pro-posed curvature sensing probe has a high sensitivity and can identify the bending direction. When bending in the X direc-tion, the sensitivity reaches 5.62 nm/m-1, and when bending in the - X direction, the sensitivity reaches 4.75 nm/m-1, which provides a new scheme for highly sensitive and direc-tionally identifiable curvature measurement.& COPY; 2023 Optica Publishing Group

• 单位
  哈尔滨工程大学