This video is taken from the EME 100 course on Lumerical University.
Transcript
This is a 1 by 2 MMI coupler with which can be used as a splitter to split power from
the single waveguide on the left to the two output waveguides on the right.
The length of the central multimode interference region can affect the transmission efficiency
to the output waveguides.
Note that we only use one port on the right side even though there are 2 output waveguides,
and this is because the device is symmetric across y=0, as well as the source mode on the left,
so we know that there will be even power splitting between the output waveguides, and we can
get the total transmission efficiency into the fundamental mode of the outputs just by using
one port at the output.
The Finding modes stage of the simulation has already been completed, so the simulation
is in Analysis mode and we can see the results of the individual cells.
Click the "eme propagate" button to run the Propagation step of the simulation after which
we can visualize the monitor results.
This can be done either by directly right-clicking on a monitor, or by selecting the monitor
in the Objects Tree and then right-clicking on the result to plot from the Result View window.
I can change the group span of the multimode region and perform the Propagation step again
which will re-calculate the EME object's results, and if the "update monitors" option is selected
the monitor results will also be updated.
I can visualize the "internal s matrix" and "user s matrix" results from the EME solver region
object.
In the "user s matrix" results, clicking the "View data" button will open up a window showing
the matrix values where row 2 column 1 gives the complex transmission coefficient from
port 1 to port 2.
To get the power transmission efficiency, I need to apply the Abs^2 scalar operation.
Interpreting S matrix results will be discussed in the next unit.