Photonics

Photonics

Bragg grating reflector: Photolithography simulation of WBG

    • Akram Akrout akram.akrout
      Subscriber

      Once simulating the impact of Photolithography and after generating the GDS file, how to find the transmission spectrum of the initial design and the one with Photolithography effect?
      In EME we can visualize be sweeping wavelength, however in the example it is an FDTD

    • Guilin Sun
      Ansys Employee

      In such case, it would be helpful that you give the example link.

      Before you export, did you simulate the result? 

      After you export, you can import it again and do simulation.

       

    • Akram Akrout akram.akrout
      Subscriber

      The link is below:

      https://www.lumerical.com/learn/video/photolithography-simulation/

      Both designs are available, do not need to import:

       

      I got annother issue with the shape of the Litho simulated:

      The shape is not completly generated:

    • Guilin Sun
      Ansys Employee

      You mean the edges are too sharp as ideal geometry? this is due to the original simulation.

      you can shift the FDTD center to check the period more closely.

    • Akram Akrout akram.akrout
      Subscriber

      Thank you fir response.

      However again could you please indicate how to find the 

       the transmission spectrum of the initial design and the one with Photolithography effect?
      In EME we can visualize be sweeping wavelength, however in the example it is an FDTD

      thanks again

    • Guilin Sun
      Ansys Employee

      As mentioned before,"After you export, you can import it again and do simulation."

      Please simulate it again to get the result.

    • Akram Akrout akram.akrout
      Subscriber

      Sorry! I cant got your point:

      I did simulation so I had the litho GDS file generated:

      what do you after export import it

      export what and import what

    • Guilin Sun
      Ansys Employee

      You said that you want to know the transmission after lithography , with supposedly manufactured structure, right?

      whether it is for initial design, or after lithography, you will need to do simulation. Otherwise I do not see how can you get the transmission. FDTD can give you broadband result.

      If this is not what you want, please elaborate more in details.

    • Akram Akrout akram.akrout
      Subscriber

      I am asking if using the model as is with FDTD as provided on the example. 
      i run the example. I obtain the new design with litho effect through the script provided in the example. 
      actually once I got this gds file with litho effect, then how to obtain the transmission spectrum? 
      the example as is, is capable to do that or I should develop my own in separate project to obtain those results. 
      The script sweeping the corrugation provide figure for bandwidth versus corrugation and band gap center versus corrugation. I think the example is capable to provide transmission versus wavelength but I don't know how.

      if the example is capable to do that could you please guide me to do it.

    • Guilin Sun
      Ansys Employee

      Finally I understand your questions.

      As a FDTD beginer, please watch some videos:

      https://optics.ansys.com/hc/en-us/sections/360007813194-FDTD100-List-of-videos

      Then try to build the ideal WBG device: just use 5 to 10 periods, otherwise it takes you too long time.  Unfortunately Ansys does not have a complete example with a few periods to refer. Usually the device is simulated by EME: https://optics.ansys.com/hc/en-us/articles/360042304234-Phase-shifted-Bragg-grating

       

      The basic 4 steps in setting up a simulation file are:

      1: set up the geometry and select the material. in ideal WBG they are rectagles with different sizes. for lithor siulated, you have the unit cell, and just need to import it, then copy and move it periodically. just for 5 periods to be efficient. remember to have a substrate.

      2: add a mode source or port, modify the source spectral bandwidth

      3: add FDTD, modify its size to include the WBG, leave about half wavelength between PML boundaries and the device.

      4: add power monitors if you use mode source, or simply add one time monitor if you use port.

      then save the file, check the material fitting memory requirement, and run. After simulation you can try to visualize reflection and transmission.

      For actual WBG it has too many periods, FDTD may take longer simulation time (and you need to modify the simulation time settings from the default 1000 fs to more) and more memory. This is why I suggest to check the memory before running a new device simulation.

      You may have different questions during this process. Please search the forum and knowledge base to get more information. In case you could not find a solution, please post your questions one at a time here and I will help you.

       

       

       

       

       

       

       

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