Intensity profile dependence of the characteristics of an arrayed waveguide grating device

As the size of an arrayed waveguide grating (AWG) device decreases with a h igh-index variable InP based material, the characteristic responses of an A WG device designed by using the simple traditional rule deviate much from t he design characteristics. As there are several approximations in the simpl e traditional design rule, it is necessary to check the validities of the a ssumptions or the approximations used in that rule. Here, the effect of the intensity profile of a wavefront freely propagating through the slab waveg uide is analyzed by comparing four different profile approximations, and th e corresponding characteristic responses are simulated elaborately by using a homemade computer simulation. The simulation with propagation mode diffr action gives characteristic responses which are quite similar to those of t he fabricated devices. Simulations with other profiles show inappropriate v ariations in that the effective channel width and the noise level deviate f rom realistic results. The simulations for a silica-based AWG show characte ristic responses which are similar to each other, and the best simulation w ith propagation mode diffraction gives a response which is quite similar to the one of the fabricated device.