Abstract
The simulation of electric fields in strongly guiding semiconductor rib waveguide Y-junctions with a new, general operator identity which yields a series of practical and easily programmed fourth-order accurate propagation algorithms is described. While the methods require 3-6 times the computation time of standard procedures for a given propagation step, they are typically more precise by several orders of magnitude for reasonably small propagation step lengths. The exact ratio of CPU times required to achieve a given accuracy, however, is somewhat problem dependent. It is noted that the procedure has been generalized to all orders.