Photonics

Photonics

Help with Exporting To GDS – Lumerical Grating Coupler Example

    • graemebargen
      Subscriber

      Hello,

      I have run through the entire example of the inverse design of grating coupler 2D from https://support.lumerical.com/hc/en-us/articles/360042800573-Inverse-design-of-grating-coupler-2D-

      I have modified the parameters for my own use. I have modified the model to create a fully etched geometry (the grating etches in the silicon device layer are the entire height of the layer, in this case 600nm). However when I export the design to GDS it does not create the proper GDS geometry in that it is not fully etched (eg. the etches should be empty space, not a polygon) as you can see from the screenshot below:

    • Taylor Robertson
      Ansys Employee
      Hello So GDS has no concept of thickness, and the gds script here exports both etched and unetched layer as two layers. Depending on what type of resist you are using in your process (positive/negative) then you could imagine building the mask using either of these layers.
      These layers are defined via layer_def argument. Simply delete the second layer definition if you don't want to include this in your gds export.
      "layer_def = [1, 0.0, {0}];".format(height)

      Best
    • graemebargen
      Subscriber

      I tried using your advice but this method still does not work. They way the example files are set up in https://support.lumerical.com/hc/en-us/articles/360042800573-Inverse-design-of-grating-coupler-2D- there is a silicon ring drawn in Lumerical and then the background material is etched out of it by drawing subsequent rings for the gratings in a different material. So exporting to GDS based on the height argument alone does not work as the silicon ring geometry object and the etch geometry objects have the same height in Lumerical for a fully etched geometry ( eg. the silicon is say, 0.5 um tall, but the etches are 0.5um tall as well just a different material)
      Do you have any other ideas how to export this properly to GDS for a fully etched grating using the example files? Is height of the geometry object the only argument that is possible to export upon?
      Thanks.
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