Scalar-wave approach for single-mode inhomogeneous fiber problems

It has generally been accepted that accurate results may be obtained using the scalar-wave approach to solve problems dealing with inhomogeneous multimode guided-wave structures. The problem of the applicability of the scalar-wave approach to obtain wave propagation characteristics in single-mode fiber or integrated optical circuit guides with inhomogeneous index profiles is examined in this paper. It is shown that if certain limiting conditions are satisfied, the scalar-wave approach will yield valid results for single-mode structures. These limiting conditions are usually satisfied by many practical single-mode inhomogeneous fibers or IOC structures.