The Fabrication of “8”-Shape Microstructured Optical Fiber and Its Application in Pressure/Temperature Sensing

A microstructured optical fiber was designed. The internal structure of the fiber consists of two round channels, and its cross-section resembles the shape of “8”. This fiber can be applied in the fields of pressure sensing and temperature sensing. The stress induced by pressure on the core increases the birefringence due to the photo-elastic effect. When an appropriate liquid material, such as glycerol, is filled into the two round channels of the fiber, temperature sensing can be achieved based on the coupling between the fiber core and the liquid rod. Both pressure and temperature sensing characteristics were investigated in detail in experiments. By constructing a Sagnac interferometer, the pressure sensitivity reached 109.78 nm/MPa. Based on the coupling between the core and the infiltrated glycerol in the round channels, the temperature sensitivity was as high as −47.15 nm/$^{\circ }$C. Their cross-sensitivities were also analyzed. The pressure or temperature sensors based on this fiber are highly suitable for scenarios such as the oil and gas industries.