ABSTRACT
An improved full-vectorial method exploiting the opposite-parity property of eigenmodes based on orthonormal-functions expansion is proposed to solve the wave equation for holey optical fibers. By use of the parity property of eigenmodes in symmetric structures, the number of orthonormal function integrals involved in the calculation is reduced, and the computation efficiency is greatly enhanced. The coupling between the two transverse field components is considered, and both dominant and minor field components can be calculated for the accurate modeling of fiber modes. This method is useful for efficiently modeling holey fibers, especially those with large air holes, in which the coupling effect that is due to refractive-index discontinuities is strong.