Photonics

Photonics

Why the TE mode cannot sustain in 220nm waveguide in 2D simulation?

    • Rabi4_
      Subscriber
    • Greg Baethge
      Ansys Employee

      A first consideration is the mode solver area is too small. You need to increase its span. Typically, we want the mode fields to be negligible at the boundaries so the boundaries are not affecting the modes.
      In any case, we'd probably need more information about your simulation settings.
    • Rabi4_
      Subscriber
      I am using the FDTD solver. I used the 2D simulation and in mode source I
    • Rabi4_
      Subscriber

    • Rabi4_
      Subscriber
      I am using the FDTD solver. I used the 2D simulation and in the mode source I used the Fundamental TE mode
    • Greg Baethge
      Ansys Employee
      Thanks for the additional information. I think an issue is how is defined TE and TM in a 2D simulation. If you look at the modes calculated by the source ("mode selection" set to "user select"):
      You can see here that TE is defined as y polarized, that is not necessarily the definition if you consider the propagation in a slab in the xz plane. So the question is to make sure you're looking at the right modes.


    • Rabi4_
      Subscriber
      I have selected the user mode in the mode source. The fundamental mode gives the TM mode. Why can't I get the TE mode as the fundamental mode for 220nm waveguide (around 1400nm to 1700nm)?
    • Rabi4_
      Subscriber
      Another observation: I can get the TE Mode as the fundamental mode when I increased the waveguide width to 500nm. However, in 220nm, I don't get the same result? WhY?
    • Greg Baethge
      Ansys Employee

      As I mentioned, the first thing is to make sure you have the same definition for TE and TM modes. With the convention we use for 2D simulations, with a source propagating along the x axis, TE is polarized along y and TM along z.
      Then, whether the fundamental mode is TE or TM is dependent on the waveguide dimensions. I don't think there's anything wrong with the modes that are found.
Viewing 8 reply threads
  • You must be logged in to reply to this topic.