This tutorial illustrates how to convert information from OpticStudio into RSoft’s propagation software and back. This can be useful for multi-stage cases in which one part of the system is a bulk optical system, and a waveguide in others. In this example, we will look at the coupling from a focusing lens into a small silica fiber.

Authored By Matthew Frank

Introduction

This tutorial illustrates how to convert information from OpticStudio into RSoft’s family of beam propagation software. This can be useful for multi-stage cases in which one part of the system is efficiently simulated in OpticStudio, and other parts (like waveguides, photonics crystals, etc.) require electro-magnetic propagation tools.

In this example, we will look at the coupling from a focusing lens into a small silica fiber via the BeamPROP software. This tutorial assumes some familiarity with the RSoft software.

Finally, while this tutorial uses the GUI in order to convert the fields, there are command line utilities in the RSoft products to do this conversion as well. Please see the appropriate appendix in the RSoft CAD manual for more information.

Getting the data from OpticStudio

In this section, we begin by opening up OpticStudio. Choose File...Open and then go to the {Zemax}\Samples\Physical Optics folder to open Fiber Coupling.zmx. You can select any of the analysis features, including the 2D layout to see how the rays focus to a point. 

Select Analysis...Physical Optics to see a 2 mm input waist Gaussian being focussed at the image plane of the lens:

From here we can tell OpticStudio to output the beam files we will need to convert into the RSoft format. Press the Settings option on the top of the Physical Optics Propagation window and then select the Display tab and click on the "Save Output Beam To:" option. Next, set the name of the file to be Fiber_output.zbf. Press OK.

These files are typically saved in the {Zemax}\POP\BEAMFILES directory so you can find the file there.

Creating the index file to be used for the BPM simulation

In this section, we will create the index file for the fiber we will be using. Open up an RSoft CAD window, and press the New Circuit icon. Set the parameters as shown below and then press OK.

Draw in a straight segment and then right click on it. Set the segment properties to look like the figure below and then press OK.

Press the Edit Pathways icon, press the New button, and then select the segment. Press the Monitors button and then the New button in the newly opened monitors window. Set the Type to Total Power and then press OK in this window and the next toolbar to go back to the CAD.

Press the Compute Materials Properties icon, and set parameters to look like the below figure.

We can now view the index profile as shown below.

Converting from OpticStudio to RSoft format

Now that we have created the structure as well as the monitors, we can proceed with setting up the launch field. Select Utility/Ray-Tracing Converters to open up the converter to change the previously created files into a format that the RSoft Software can use. (Note that we refer to this as a 'ray-tracing conversion', although the OpticStudio result is a Physical Optics Propagation and therefore not a ray-tracing result per se.) From here we will convert the files that were created in the earlier ray-tracing packages. Be sure to save the relevant files from the ray-tracing tools to the appropriate working directory where the index file is located.

Set the selection to be from OpticStudio to RSoft and then use the appropriate menus to set up the *.ZBF file to be used as shown below.

Press OK to convert the file and view the plot of the conversion.

Please note that the corresponding data file is complex, and contains phase information as well. The phase information for this specific case is displayed above. To display this plot, select Edit/View and then change the output to read the @odd information instead of the @even data.

Setting up the launch field

Finally, we have to use these converted fields as the input source. Go back to the RSoft CAD, and press the Edit Launch Field icon. Set the launch parameters match those below and then press OK.

Running the simulation

Press the Perform Simulation icon and set the Display Mode to Contour Map XZ. Press the Output button and set the window to look like the figure below.

Press OK to go back to the simulation window. Enter bpoutput in the Output Prefix box and then press OK run the simulation.

As we can see, the coupling from this lens from OpticStudio has about a 77% coupling into this particular fiber.

Note also that data can be easily converted from RSoft format to OpticStudio so that an easy bi-directional interface exists between the two codes.:

KA-01472