May 24, 2023 at 7:02 amPo-Yu HsiaoSubscriber
I am trying to design a Y-branch combiner that connects three single-mode waveguides(only fundamental TE and TM modes allowed).
First, I used MODE to check whether a waveguide is single-mode. As shown in the attachment, the waveguide only showed two fundamental guided modes (TE & TM) when the number of mesh cells is set to 800 in x and y.
Thus, I used this waveguide to design a Y branch and set a fundamental TM mode source injecting from the right-upper port(Please refer to the attachment) in FDTD. However, I found the output port showed a mode that is neither fundamental TE nor TM mode. I think only the fundamental TE and TM modes are allowed and will be guided in this waveguide. Why does this happen? Is this because the mesh of FDTD is too coarse?
May 24, 2023 at 10:43 pmGuilin SunAnsys Employee
This post has been replied in Zendesk support. For the benefit of other users, I give a short reply here:
Most likely there are other higher order mdoes that are excited due to bending and waveguide geometry change. To check if the waveguide supports higher order modes, please use more numer of trial modes.
May 27, 2023 at 1:50 pmThen ElangoSubscriber
Hi, I think changing the mesh settings will not affect the number of modes in the waveguide. Because Meshing posint would be required to determine the accuracy of the system.
Is this assumption right?
May 29, 2023 at 3:49 pmGuilin SunAnsys Employee
Not necessarily right. you can try to use 2*2 mesh and check the result. FDE solves eighgen values so it needs some details of the structure.
The most important thing is: when Metal BC (the default BC for mode expansion monitor) is used it has box modes, which are not necessarily the propagation modes, whereas using PML BCs can have a lot of PML modes that need to e removed. Since you set a certain number of tiral modes, when the solver reaches this number it will stop, so some higher order modes may not be found.
May 29, 2023 at 4:42 pmThen ElangoSubscriberThank you for the detailed reply.
- You must be logged in to reply to this topic.
Boost Ansys Fluent Simulations with AWS
Computational Fluid Dynamics (CFD) helps engineers design products in which the flow of fluid components is a significant challenge. These different use cases often require large complex models to solve on a traditional workstation. Click here to join this event to learn how to leverage Ansys Fluids on the cloud, thanks to Ansys Gateway powered by AWS.
Earth Rescue – An Ansys Online Series
The climate crisis is here. But so is the human ingenuity to fight it. Earth Rescue reveals what visionary companies are doing today to engineer radical new ideas in the fight against climate change. Click here to watch the first episode.
Subscribe to the Ansys Blog to get great new content about the power of simulation delivered right to your email on a weekly basis. With content from Ansys experts, partners and customers you will learn about product development advances, thought leadership and trends and tips to better use Ansys tools. Sign up here.
- Why am I getting “process exited without calling finalize”, and how do I fix it?
- “Import optical generation” or “delta generation rate”?
- Error: addfdtd is not a valid function or a variable name
- Error on Lumerical device
- Using a license file on a new license server
- Ansys Insight: Transmission results greater than one
- Finding your Ansys (or Lumerical) account number
- Ansys Insight: Diverging Simulations
- Ansys Insight: Why my simulation result is different from published paper or experiment?
- Is there a Lumerical script command to output the Simulation and Memory requirements?
© 2023 Copyright ANSYS, Inc. All rights reserved.