Zone and FAST
Zone and FAST (Flexible Algorithm Selection Technology) are related techniques that simulate the propagation of light in user-specified calculation windows, which may be at any location and any angle in the design. The module can combine multiple zones (that use different simulation settings or algorithms) in a single simulation run.
A simulation zone behaves just like any other layout element; its ports can be placed anywhere in a design. Its parameters determine the simulation settings; for example, the algorithm to use (BPM or FDTD) and the spatial and temporal grid size. If two simulation zones touch, or overlap each other, they are combined in a single simulation, in which the end field of one simulation zone is passed into the next zone automatically. Non-touching zones can also be linked by means of linked mode launchers, whose amplitude and phase can be modified values from a simulation in a previous zone.