The Loss Characteristics of Curved Fiber at Small Radius

Curved optical fiber sticking onto a round structure has many applications, such as mandrel acoustic sensors and fiber-length scratchable phase modulators. However, the components' performances are limited by the transmission loss of the wound fibers. In this paper, the bending loss characteristic of curved fiber at small radius is theoretically analysed and experimentally demonstrated. A modified five-layer slab waveguide theory is used, which indicates that the bend loss has distinct oscillations at small radius. When the bending radius is smaller, the oscillation period changes more observably. In the experiment, single-mode fiber is bended on the outer surface of cylinders with various radius. The experimental result is consistent with theoretical analysis one.