Tilted fiber Bragg gratings in multicore optical fibers for optical sensing

Abstract

[EN] We have inscribed a tilted fiber Bragg grating (TFBG) in selected cores of a multicore optical fiber. The presence of the TFBG permits to couple light from the incident guided mode to the cladding modes and to the neighbor cores and this interaction can be used for optical sensing. We have considered to measure different magnitudes: strain, curvature magnitude and direction and external refractive index. The curvature results show a linear dependence of the maximum crosstalk with the curvature magnitude with a sensitivity of 2.5dB/m-1 as the curvature magnitude increases and at the same time a wavelength shift of 70pm/m-1. Changes in the external refractive index gradually vanishes the cladding modes resonances and the crosstalk between the different cores obtaining a reduction of the 90% of the optical spectra integral area for refractive indexes between 1.398 to 1.474.