ポリマー光ファイバーを用いた高解像度・高感度クロスカープリング法に基づく変位センサー

Most displacement sensors offer high resolution but suffer from limited sensitivity and measurement range. Typically, increasing the range results in a reduction in both resolution and sensitivity. This study presents a novel displacement sensor based on a spiral-structured polymer optical fiber that operates through intensity modulation via bend-induced coupling. Controlled spiral bending generates radiative loss, which is coupled by strategically positioned secondary fibers. The sensor comprises two segments: a spiral-shaped primary fiber that generates controlled radiative losses through macro-bending, and a vertically movable secondary fiber that couples the radiated optical power to quantify displacement. A custom 3D-printed experimental platform with a guiding groove was developed to ensure precise alignment and minimize axial motion. Experimental results demonstrate a displacement measurement range of up to 20 mm, with high sensitivity of 3.26μW/mm, resolution (30.67 nm), excellent repeatability, and stable response. The proposed sensor provides a compact, cost-effective, and flexible solution for distributed displacement monitoring in various applications.