A highly sensitive strain fiber sensor based on waved core structure

Strain and temperature, as two important parameters to evaluate structural health, is increasingly paid numerous attentions for years. In this article, we developed and experimentally tested a highly sensitive strain sensor based on SMS structure with waved core multi-mode fiber (MMF), which has ability to monitor temperature simultaneously. By introducing a section of bent-core fiber into the portion of MMF, the higher-order cladding mode is excited to enhance the sensitivity. Furthermore, the portion of bent-core displays significant influence on effective refractive index (ERI) of the MMF section as strain applied, which brings about higher strain sensitivity. The experimental results display that the highest sensitivity of the sensor reaches 125.5 pm/mu epsilon within 0-200 mu epsilon and the measuring range achieves 0-1200 mu epsilon. By demodulating two dips, simultaneous measurement for strain and temperature is achieved by solving the equation matrix. This simple method displays minor influence on mechanical property and enhances the strain sensitivity considerably. It is strongly believed the proposed sensor brings about a competitive choice in engineering fields.