Photonics

Photonics

Ring Resonator using Lumerical FDTD

    • bublee-2016114988
      Subscriber

      Hello, I was actually trying to replicate a paper with a Si ring resonator. And I could not even get a proper drop output. 

      I mean I could replicate the one given on the Lumerical website in one try, but just when I change the parameters to match the paper, it just doesn't work.

      I am attaching the file below, I would really appreciate it if someone could take a look and point out my mistakes.

      https://drive.google.com/file/d/1jd05cKvsVxeOVOEQ8a0xVcsyA5FwVn4p/view?usp=sharing

      Here are the specifications:

       

    • Guilin Sun
      Ansys Employee

      Duplicating published results many a time is very challenge, as you may not get exactly the same parameters, including the device material, simulation settings. Please refer https://forum.ansys.com/forums/topic/ansys-insight-why-my-simulation-result-is-different-from-published-paper-or-experiment/

      Suggestions:
      please use overrid finer mesh for the particle region, and the coupling region. Make sure the material is correct and simulation time is long enough with smaller than autoshutoff min.

    • bublee-2016114988
      Subscriber

      Thank you for your reply.

      Yes, of course I don't expect to get the exact same results, but the thing is I keep getting almost an increasing exponential at the drop output. That's why I thought maybe I was making some kind of a mistake. Also, if I change the wg width to 400 nm instead of 200 nm as given here, I start getting the characteristic curve of a ring resonator.

      I will try the override mesh region and get back to you.

    • Guilin Sun
      Ansys Employee

      Coupling (both the bus to ring and particle to ring) is critical. If there is no proper resonance you will see something not usual.

      • bublee-2016114988
        Subscriber

        How do I couple the particle to the ring?

    • bublee-2016114988
      Subscriber

       

      This is my simulation region:

      This is the drop output I got:

      I added the mesh override region at the coupling regions and added no nanoparticles here. But I got this output. I have no idea why it does not work.

      Attaching my file below:

      https://drive.google.com/file/d/1PFeVl-7pBINuV4wfc_eQZLDx_Oak_HjZ/view?usp=sharing

       

       

       

       

    • Guilin Sun
      Ansys Employee

      Port2 is the source port? it is reflection.

      Please check the transmissions. It might be due to small coupling.

      you can also add override mesh to the particle since it is small.

      • bublee-2016114988
        Subscriber

        Port 1 (upper left) is the IN, port 2 (lower left) is the DROP, port 3 (upper right) is the THROUGH, and port 4 (lower right) is the DROP 2.

        If the coupling is indeed small, what should I do? Because as I mentioned earlier, changing the wg width to 0.4 μm from 0.2 μm works. 

        The output that I have given does not have the Au particle, so I didn't feel the need to add mesh override region.

    • Guilin Sun
      Ansys Employee

       

      As your result shows, the coupling depends on both the gap and the waveguide size. When you could not find the coupling as expected, please optimize them, either the waveguide or the coupling region and gap, or both. I did not find any significant issue in your simulation settings from the screenshots.

      Using override mesh or not is up to you. Simulation is a design process so you will need optimize some critical parameters of the device, with proper simulation settings. Please follow the online examples.

      Please noite that this forum is to give help for general questions. It is not targeting a specific issue. If you have premium support privilege, please send us email for support.

      We can also isolate the issues. For example, one post is for the case with nano particle, and the other for without nano particle.

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