Simultaneous temperature and bend sensing with long-period fiber gratings

Long-period gratings (LPG’s) written in commercially available boron-codoped fibers operating at wavelengths of $<1.1 \mathit{\mu }\mathrm{m}$ are shown to exhibit high temperature and bending sensitivities. Each resonant attenuation band of such LPG’s was observed to split in two when the LPG’s were bent. The split attenuation bands’ separation increased significantly with increasing bend curvature, and the central wavelengths of the split bands provided a measure of temperature. We exploit this effect to allow for simultaneous measurement of temperature and bending in smart-structure applications. The demonstrated novel sensor system is simple and low cost.