A new beam propagation method (BPM) based on the expansion of a global basi
s function is introduced for the numerical simulation of field propagation
in optical waveguides. In dealing with the boundary truncation problem, tan
gent-type variable transformation is applied. To show the validity and usef
ulness of this approach, numerical results are shown for guided-mode propag
ation in a straight slab waveguide and TE-wave propagation through a tapere
d slab waveguide. (C) 2000 John Wiley & Sons, Inc.