SCALAR DIFFRACTION THEORY APPROACH TO ESTIMATING MULTIMODE-WAVE-GUIDEFIELD-AMPLITUDE MODE DISTRIBUTIONS

We introduce a method to estimate the coupling coefficients of the gui ded field amplitude and the corresponding angular bandwidth in a multi mode slab waveguide. This scalar diffraction theory approach is simple r than the more rigorous electromagnetic treatment and is directly app licable to communications systems that use large (dimensions or numeri cal aperture) waveguides, as in substrate-mode interconnects. Moreover , this method provides conceptual insight as to a parameter's effect o n the field-amplitude mode distribution and angular bandwidth. (C) 199 8 Optical Society of America.