Broad-Wavelength-Range Strain Dependence of Modal Interference Spectra in Acrylic-Based Polymer Optical Fibers

We experimentally observed modal interference spectra over a broad wavelength range in polymethyl methacrylate (PMMA)-based polymer optical fibers (POFs) and then investigated their strain dependence. At around 1550 nm, we obtained a wavelength shift of about -17 nm/% under applied strain, representing the strongest sensitivity within the spectral range covered. We infer that the critical wavelength lies above 1600 nm, and by also considering the wavelength dependence of propagation loss, we established guidelines for selecting the optimal wavelength region when implementing PMMA-POF-based strain sensors.