nanoHUB U Nanophotonic Modeling/Lecture 2.10: S4 GUI Input
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[Slide 1]  Everyone, welcome to lecture 2.10. So in the last lecture, we just introduced the S4 program. 

[Slide 2] Which can be used to calculate S matrix for realistic geometries. This is just an example. And there's actually not just purely the text-based interface that we talked about last time, which is in LUA. But then there's another interface, which is a graphical user interface that our group constructed on NanoHub. And so if you go to this website, nanohub.org/tools/s4sim/ then you can actually access the graphical user interface with a free NanoHub account. 

[Slide 3] And so, first of all, what kind of interesting examples can we do? So, here we're actually showing all the examples that are kind of built in here. And so, though it's a bit hard to read, there's a whole bunch of examples, many of which are drawn from the literature. And so you can actually not only run this calculation but then you can compare to the citation that's alluded to here. For example, this, and then compare your figure and your outputs to the output that's shown. And of course, we'll mainly be covering input in this lecture but next one, we'll see what the output would look like. 

[Slide 4] So let's say however that instead of just reproducing stuff that's already in the literature, you want to create your own structure. So in this case, again, much like with the text-based interface, we need to choose our own material. But the one advantage potentially of this graphical user interface is that we can create not only a user-specified material with a specific epsilon. But we can also pick realistic materials, like say, gold or silicon dioxide that may have certain dispersion values. So basically, epsilon changing with frequency, and so on. And so then that's shown here. 

[Slide 5] And what we can do next is actually based on the materials that we create, we can create layers. And we can choose either just a single layer and then have semi-infinite boundaries on either side or we can actually stack many layers together. And then the layer stacked together can be aperiodic or they can be periodic. And there's a special function that basically allows us to choose the periodicity, and I think we're limited to certain number of total unique layers which would be ten and certain number of periodic repeats, which is probably at least five or ten. So you could have up to 100 layers, probably. 

[Slide 6] And then you can see here that you can actually specify more details about the layer configuration here. And so you can actually choose several different factors. So for example, you can choose the type of the layer periodicity and the lateral direction. So you could choose like a circle or square and so on. And then you could choose the center of that square or circle and then you choose the radius, and so on. So, you get to pick all these geometric parameters that are important in specifying your structure. And you can also, kind of, selectively switch different materials as need be, repeating materials if needed or choosing unique materials. I think we're limited to ten unique materials in this current framework. 

[Slide 7] And then there are other parameters that are very important for a simulation, analogous to what we had covered last time so particularly the angle of incidence in polar coordinates as well as the S polarization amplitude and phase. And then the p amplitude phase. And then we also get to choose the periodicity in real units, and then we can choose the wavelengths in real units. And so of course, this is designed for optics, so typically, you pick something invisible or infrared. And then, we have a few other minor options that are here. So in the next lecture, we'll talk in more detail about what kind of outputs can we get from this sort of system.