The propagation of modes in magnetooptic waveguides distinguishes betw
een the forward and the backward direction. This effect is applied to
the realization of integrated optical isolators and circulators, The p
aper presents a finite-difference beam propagation simulation of such
devices. Two different directions of the waveguide magnetization are c
onsidered. Finally, some Consequences with respect to the practical re
alization of nonreciprocal integrated optical components are discussed
.