Field deformation and loss by curvature in gain guided and index anti-guided fibers

Gain guided and index anti-guided fiber, being a new kind of fiber with a great potential application on large mode area lasing devices, has the inevitable geometric curvature, which induces field deformation and bending losses. In this paper, the method of complex-value extended Fourier-Bessel series is introduced on optical field deformation and bending losses by geometric curvature in the case of this new fiber. Comparing with conventional fibers, gain guided and index anti-guided fiber has better performance on anti-curvature; the quantity of optical intensity centre being shifted from fiber geometric center is less than the case of conventional index guided fibers; and the bending losses decrease dramatically with the increase of curvature radius.