Nondestructive imaging of a type I optical fiber Bragg grating

Abstract

The nondestructive images of refractive-index variation within a type I fiber Bragg grating were recorded by the differential interference contrast imaging technique. The variations in the refractive index within the core appeared as uniform horizontal rows that have periodicity equal to that of the phase mask. The images revealed detailed structure within the fiber core that is consistent with the formation of Talbot planes in the diffraction pattern behind the phase mask.