A High-Precision D-Shaped Fiber Polishing Method and its Sensing Characteristics of Different Polishing Depths

In this paper, a simple and low-cost side-wheel polishing machine was designed and fabricated to enable the fabrication of D-shaped optical fibers. Scanning electron microscope (SEM) characterization of the fabricated polishing fiber cross section confirms the high precision of the polishing machine. The optimal parameters for the preparation of D-shaped SPR sensors were determined by simulation. A gold film was coated on the surface of D-shaped optical fibers with different polishing depths to realize the surface plasmon resonance (SPR) effect and used it for refractive index (RI) detection. The sensitivity of the sensor reached a maximum of 3317.14 nm/RIU in the range of 1.341–1.400, which proves the effectiveness and usefulness of the D-shaped fiber that was polished. This polishing machine can meet the needs of the laboratory and is expected to realize the batch production of D-shaped optical fiber, which provides better support and guarantees for the development of D-shaped optical fiber sensors in the fields of biosensing and environmental monitoring.