Open channel exposed core microstructured fibers for sensing both pressure and refractive index

An open channel exposed core microstructured fiber is designed and fabricated for pressure and refractive index sensing. The core is on a flat platform surrounded by the cladding on which there is an open gap that allows the surrounding medium to contact the core. Due to the specially designed microstructure, the external pressure compresses the fiber core and causes changes of birefringence because of the photo-elastic effect. As the core is exposed, the mode effective refractive index is significantly affected by the surrounding refractive indices. Such developed fiber sensor exhibits an extremely high sensitivity for pressure which is -0.293 nm/kPa (0 to 240 kPa) and refractive index sensing, achieving -4461.74 nm/RIU (1.332 to 1.350). This fiber is promising in application scenarios like the gas/oil industry, water treatment, and maritime monitoring.