Theoretical study of Electro-optic effect and elasto-optic effect in chirped fiber grating with uniaxial crystal materials cladding

A chirped fiber grating with cladding made of uniaxial crystal material whose optical axis is parallel to the axis of grating, i.e., z-axis is proposed. Electro-optic effect and elasto-optic effect in this kind of fiber gratings are theoretically analyzed for the first time. The influences of the electric field and the strain applied to the fiber grating cladding along z-axis on Bragg wavelength lambda(B) and the reflectivity spectra of this kind of chirped grating are theoretically examined using coupled-mode theory and transfer matrix method. The curves of Bragg wavelength lambda(B) as a function of an external electric field or the strain are theoretically obtained respectively for three kinds of uniaxial crystal materials as the grating claddings. The calculated results indicate that when the axial electric field applied to the grating cladding varies from 1 x 10(7) to 8 x 10(7) V/m, lambda(B) has the decreases of 0.12 nm, and when the applied strain varies from 0 to 0.04, lambda(B) has the decreases of 0.45 nm.