Albane Laronche

TL;DR: The experimental results show that the wavelength separation between selected resonances allows the measurement of the refractive index of the medium surrounding the fiber for values between 1.25 and 1.44 with an accuracy approaching 1x10(-4).

TL;DR: In this paper, a hybrid structure made of a long period grating (LPG) and a tilted fiber Bragg grating was proposed to measure the curvature of a beam by the reflected power difference between the core and the recoupled cladding modes.

Abstract: A novel fiber optic bend sensor is implemented by using a re-grown tilted fiber Bragg grating (TFBG) written in a small core single mode fiber with UV overexposure. The spectrum of the re-grown TFBG contrasts with that of normal TFBG by exhibiting large differences in the amplitude between neighboring symmetric (LP0m) and asymmetric (LP1m) cladding mode resonances, moreover each asymmetric cladding mode resonance splits into two peaks (corresponding to two orthogonal polarization states). The differential response of the three individual resonances of such group provides quantitative information about the magnitude and directions of bends in the TFBG. Numerical simulations indicate that the changes in the cladding-mode profiles in a bent fiber are responsible for this behavior through their impact on coupling coefficients. A bend sensitivity of 0.4 dB. m (for the 18th order group of cladding modes) is experimentally demonstrated within a range of 0-10.6 m- 1.

TL;DR: Three kinds of resonances whose relative sensitivities to strain, temperature and refractive index are markedly different are identified and numerical simulations are presented to explain these properties.

TL;DR: In this paper, a novel technique for simultaneous measurement of refractive index and temperature based on power level detection of a weakly tilted fiber Bragg grating (TFBG) is proposed and experimentally demonstrated.