Hollow square core fiber sensor for physical parameters measurement

The measurement of physical parameters is important in many current applications, since they often rely on these measurands to operate with the due quality and the necessary safety. In this work, a simple and robust optical fiber sensor based on an antiresonant hollow square core fiber (HSCF) is proposed to measure simultaneously temperature, strain, and curvature. The proposed sensor was designed in a transmission configuration where a segment of HSCF, with a 10 mm length, was spliced between two single mode fibers. In this sensor, a cladding modal interference (CMI) and a Mach-Zehnder interference (MZI) are enhanced along with the antiresonance (AR) guidance. All the present mechanisms exhibit different responses towards the physical parameters. For the temperature, sensitivities of 32.8 pm/°C, 18.9 pm/°C, and 15.7 pm/°C were respectively attained for the MZI, AR, and CMI. As for the strain, sensitivities of 0.45 pm/με, -0.93 pm/με, and -2.72 pm/με were acquired for the MZI, AR and CMI respectively. Meanwhile, for the curvature measurements, two regions of analysis were considered. In the first region (0 m⁻¹ - 0.7 m⁻¹) sensitivities of 0.033 nm/m⁻¹, -0.27 nm/m⁻¹, and -2.21 nm/m⁻¹ were achieved, whilst for the second region (0.7 m⁻¹ - 1.5 m⁻¹) sensitivities of 0.067 nm/m⁻¹, -0.63 nm/m⁻¹, and -0.49 nm/m⁻¹ were acquired for the MZI, AR and CMI, respectively.