Twin-core Photonic Crystal Fiber for In-Line Torsion Sensor

We present the in-line torsion sensing scheme using the twin-core photonic crystal fiber (TC-PCF). An in-line Mach-Zehnder interferometer can be effectively configured by splicing a section of TC-PCF between two SMFs. The torsion sensitivity was measured by monitoring the twist-induced spectral fringe shift. The channeled spectrum was found to shift bi-directionally as the twist rate was increased. The peak wavelength shifts toward longer wavelength sides then the shift rate is gradually reduced. Finally the peak wavelength shifts toward shorter wavelength region with the increased twist rates.