Start by opening the create_dataset.lsf script file.
This script file calculates the fields for a radially-polarized Gaussian beam.
The method used to calculate the fields of the radially-polarized beam is similar to
the method for calculating the field profile for a Gaussian source when using the thin
lens method, but instead of having a linear polarization direction, the field components
The fields are defined in the XY plane so the source will propagate along the z-axis.
In the section of the script shown here, the electric field data and corresponding x and
y position parameters are packaged into a rectilinear dataset and then saved to a .mat
The .mat file will be saved to your current working directory when you run the script
Add an import source from the sources drop down menu.
Edit the source and click the Import Source button which opens up a file browser.
From the file browser, you can choose the file type to look for, either .mat or .fld.
Select the import_data.mat file and click the Open button to load the data.
Now that the data is loaded, you can see that the injection axis is fixed to the z-axis.
The imported source settings show information about the center position of the field data
that has been imported as well as the wavelength if wavelength data was specified in the dataset.
Under the geometry tab, the spans of the source are also fixed and they correspond to the
area over which the fields from the imported dataset are specified.
However, the center position of the source can still be modified to shift the position
of the source.
The wavelength injected by the source can still be under the Frequency/Wavelength tab,
and doesn't have to match the wavelength specified in the imported data set.
Set the wavelength to 0.5 um.
If injecting over a broadband range, you can use the multi frequency field profile option.
You can use the Visualize Data button to view the imported field profile, and the Clear
Data button to clear the field data.
Click OK to accept the settings.
Click the run button, and after the simulation completes, right-click on the profile monitor
and visualize the electric field profile.
You can see that this matches the field profile that we loaded.
From the vector plot, you can see that the fields are radially-polarized.
Here is some useful information for setting up import sources.
The data that you load doesn't need to be sampled on the same grid as the simulation
mesh and they can be defined on a uniform or non-uniform grid.
The fields will automatically be interpolated onto the simulation mesh so you don't have
to worry about the exact locations where the fields are defined.
There are no rotation settings for the import source, so if you if you want to apply an
additional rotation to your source to inject the fields at an angle, one way you can do
this is by importing the original field data and measuring the injected fields across an
angled plane in front of the source.
You can then use the data from the angled plane as the data to import for the simulation
where you want the fields to propagate at an angle.
You might want to use the angled monitor analysis group from the Object Library to do this.
A link is provided below for more information about the angled monitor group.
If using the import source to split up a larger simulation region into two simulations like
the case discussed in the previous unit, keep in mind that any light which might get reflected
back and forth between the two separated parts of the structure won't be taken into account.
This method will decouple the two parts of the structure, so only use this method if
you expect that multiple reflection events will have negligible impact on the performance
of the device.