Confinement loss evaluation based on a multilayer division method in Bragg fibers.

Confinement loss is comprehensively evaluated for TE, TM, and hybrid modes of Bragg fibers using a multilayer division method newly developed. We show the loss dependence on the core radius, wavelength, cladding index contrast, and the number of cladding pairs. The confinement loss is reduced in proportion to (a/b)(2N) and (n(2) (b)b/n(2) (a)a)(2N) for the TE and other three modes, respectively, with respect to cladding pairs N under the quarter-wave stack condition, with cladding high na and low indices nb and their corresponding thicknesses a and b. For sufficiently large core radius, the confinement loss decreases in inverse proportion to the third and first powers of core radius for the TE and other three modes, respectively. Low loss modes are the TE(01), TE(02), HE(13), and TE(03) modes in order of increasing confinement loss.