| Two-core fiber is special designed fiber, in which contains a pair of parallel fiber core surrounding a cladding with diameter 125μm. Based on the two-core fiber, a series sensing characteristics have been developed and investigated in this paper.One of interesting sensor is fiber curvature sensor that uses two-core fiber as the sensing element has been proposed and demonstrated. The two-core fiber act as a two-beam in-fiber integrated interferometer in which phase differences is a function of curvature in the plane containing the cores results in the shift of the far-field interferometric fringe pattern. The other one, for instance, a twisting angle sensor is also investigated and discussed.A low-coherence laser diode at wavelength 650nm illuminates the two-cores and the interferogram pattern in the far-field is recorded by a CCD camera. The relationship between the far-field fringe pattern intensity distribution and the changes due to disturbing in the case of bending or twisting angle measurement have been established and experimental results were also confirmed this. |
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