OpticStudio supports the input of mode field data from Optiwave's OptiBPM and OptiFiber codes. This makes it easy to improve the accuracy of fiber and waveguide coupler designs using Physical Optics in OpticStudio by providing more accurate input data. This article gives several examples.

Zemax LLC thanks Steve Dods of OptiWave Corporation for supplying the SMF-28 fiber simulation data used in this article.

Authored By Mark Nicholson

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Introduction

OpticStudio has the ability to import the modal field computed by OptiWave Corporation's OptiBPM and OptiFiber codes.

These codes are specialized integrated-optics codes which produce field distributions for optical fiber or waveguides integrated on a substrate, including channel waveguides, rib or ridge waveguides, etc. This allows fields computed by these specialized codes to be propagated through bulk optical systems in OpticStudio. OptiBPM and OptiFiber can both read the ZBF files produced by OpticStudio so that the results of Physical Optics Propagation through an optical system can be used as the input to one of their waveguide models.

In this article, we will compare the OptiBPM simulation of SMF-28 fiber to the manufacturer's datasheet.

Importing the OptiBPM field distribution

OptiBPM and OptiFiber share a file format (*.f3d) which is proprietary to OptiWave Corporation. OpticStudio can read this data via: File...Convert...OptiWave F3d To OpticStudio ZBF.

The details are described in the help file, but note the following points:

• ZBF files have a number of pixels in x and y which must be a power of 2: the .f3d files do not. OpticStudio will therefore zero-pad the .f3d data to make it equal the nearest larger power of 2
• .f3d files do not contain the wavelength of the data, which must therefore be entered separately
• The .f3d E-field phase data is referenced to a local plane. OpticStudio will fit a Gaussian beam to the E-field data to estimate the pilot beam properties required for subsequent propagation in OpticStudio and store this data in the ZBF file.

The ZIP file attached to this article contains an OptiBPM simulations of SMF-28. The beam can be converted and then read into OpticStudio like so:

Inputting this beam and analyzing it with the POPD operand, with data 23, 24, 25, 26, shows the following:

• Effective width in x: 4.490 microns
• M² in x: 1.02
• Effective width in y: 4.478 microns
• M² in y: 1.02

The modal field as computed by OptiBPM is therefore very slightly asymmetric, and very slightly non-Gaussian (the M² parameter = 1 for any pure TEM_x,y mode). The simulation is certainly within the specification of a modal field diameter of 9.2 ± 0.4 µm.

References

Optiwave Photonic Software. 2019. OptiFiber Overview. https://optiwave.com/products/component-design/optifiber/optifiber/.

Optiwave Photonic Software. 2019. Introduction to OptiBPM. https://optiwave.com/optibpm-manuals/bpm-introduction-to-optibpm/.

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