Highly Sensitive Two-dimensional Bending Vector Sensor Using an Elliptic Two-core PCF

A highly sensitive and simple all-fiber interferometric two-dimensional (2D) bending vector sensor is demonstrated. Fiber interferometer works in reflection mode and formed by manually splicing a small section of elliptic two-core photonic crystal fiber at the end of a single-mode fiber. Due to the birefringence nature of the two cores, the fiber device exhibits orientation-dependent bend sensitivity which is different for different polarization states. A high sensitivity of 6.49 nm/mm is achieved for bending along the x-direction, and the rms deviations for bending in the x- and y-directions are estimated to be 0.015 and 0.098 mm, respectively, by using the matrix method. The device is immune to bend-induced power fluctuation.