Effect of Hot‐Water Tapering on Acrylic Polymer Optical Fibers

Hot‐water tapering was experimentally applied to step‐index polymer optical fibers made of poly(methyl methacrylate) for the first time. The effects of immersion time and tensile speed on transmission characteristics and taper geometry were investigated. Immersion up to 600 s caused no noticeable change in loss, while tensile speeds of 0.1–10 mm/s produced only gradual increases up to ~100% strain, followed by rapid growth with whitening at 120%–130%. The minimum waist diameter was ~360 μm. These results confirm the feasibility of this technique and its potential for Brillouin‐scattering‐based polymer optical fiber sensing. © 2025 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.