Split-operator electric field reflection techniques

The authors have analyzed several approximations for the reflection coefficient of an electric field incident on the interface between two inhomogeneous dielectric media. While existing expressions agree with exact results in certain limits, realistic waveguides with discontinuous refractive index changes are often more accurately modeled by dividing the incoming electric field into segments coinciding with the intervals over which the interface is continuous, and subsequently superimposing the reflection from each segment.>