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    • #50837
      Manoranjan Minz
      Participant

      I have two waveguides, one single TE mode waveguide and another multimode waveguide that supports 3 TE modes. Waveguides are placed close to each other and I want study power coupling for the fundamental mode excitation of the single mode waveguide. So, when fundamental mode of single mode waveguide is excited, how do I calculate how much power is coupled to TE0, TE1, and TE2 of multimode waveguide?

    • #50846
      Scott Newman
      Moderator

      Hello Manoranjan,

      If I remember correctly you are using OptiFDTD 14.0 which means you have access to the S-Parameters feature within the product. What you would do in this case is set one S-Param port across the single mode waveguide and set it as the input with that fundamental mode. Next you would set a second S-Param port across the multimode waveguide and configure it to the TE0 mode and run the S-Parameter script. This would give you S12 which would be the coupling coefficient. You would then repeat this process changing the mode of the second port to the TE1 and then the TE2 modes. Further documentation can be found in the technical background document that is included in the help menu in your product.

      Scott

    • #50847
      Manoranjan Minz
      Participant

      Thank you Sir,

      I believe S-parameter port works only for 3-D structures. Is there any way I can do it in 2D structures?

      ~Manoranjan

    • #50886
      Scott Newman
      Moderator

      Hello Manoranjan,

      You are correct that the S-parameter port works only for 3D simulations. In order to do this for a 2D simulation you would need to do this manually. You would set observation lines across the single mode waveguide on the input side and across the multimode waveguide on the output side. You would also set input planes at these same locations.

      You would use the input planes (configured for 2D modal)and the built in mode solver to calculate the modes. You would then use these modes with the fields along the observation lines and mode expansion to extract the components in the field for each of the modes. The equations for this are in the OptiFDTD documentation for the S-Parameters.

      Scott

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