Guilin Sun
Ansys Employee
A1: No need to include the 10um long, as its back end may only have Fresnel loss, which you can correct the transmission later. You can also develop an algorithm to take this cavity into consideration. This is more a theoretical work. But you can try one or two simulations to include it and compare the cases with truncated substrate by PML.
This 10um substrate may be supported by another material, such as glass. otherwise it is so thin and can be fragile.
A2: Oblique incidence works fine w/o the substrate end surface.
The problem is, if you want to count the back end effect, since now the grating-back-end forms a cavity, simulation should be long enough to let the pulse decays sufficiently with enough round-trips. Thus it needs long simulation time.
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