Bi-oblique propagation analysis of symmetric and asymmetric Y-junctions

A novel finite difference beam propagation method (BPM) analysis based upon a bi-oblique coordinate representation is presented. The analysis yields a computationally efficient algorithm that permits accurate simulation of a wide variety of structures to be made without staircase approximations. Further, the independent paraxial and wide angle approximations, centered upon the direction of optical field propagation in each branching waveguide, may be incorporated into the algorithm. This feature allows a low-order approximation to be used in the algorithm even if one or both of the branching angles is large. The approach has been applied to both symmetric and asymmetric optical waveguide Y-junctions and produces results in excellent agreement with those in the literature.