Abstract
This paper presents the introduction about fiber periodic structures which have a ability to coupling light from fiber core to cladding, their principles and applications. Paper also presents the detail description of particular example of TFBG spectral response for changes of fiber bending in range of curvature radius from 30 to 7 mm. The area of observed cladding mode resonances is changing due to strengthening of fiber curve with simultaneous core mode independence for this quantity. The ghost mode which is resonance closest to Bragg mode wavelength also stands out with transmission loss dependency from fiber bending which is also described.