Home Forums FDTD PWE method

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• #15726
Saurav Chanda
Participant

I need a bit of help, “Whether it is possible to compute band structure of photonic crystal slab using PWE method in opti FDTD?” If yes, then how to compute.

• #15728
perveen akhter
Participant

Do you have a periodic structure or just a slab?

• #15734
davcm
Participant

Hello Saurav,
I supose you have your PhC if not, there are lot of examples in the tutorial downloades after the Optiwave’s instalation. When you have it, you go to the Simulation tab and then click in the ‘PWE band solver Parameters’. There you have to tell the programm if it is a 1D, 2D or 3D PhC. Then you’ve to determine the supercell (if it is periodical and homogeneous by simulating for only one cell its okay (asure you to have well defined the cell. That means, your minimun peridical structure is inside the cell). You also have to tell the programm the number of bands you need to calculate and also the path you want to travel along in the minimun Brillouin Zone (k-vector Path).

After that, just press the ‘run’ button.

Regards,

David.

• #15744
Saurav Chanda
Participant

Parveen,
Yeah..Definitely it is periodic in two dimension, but it has finite thickness in the plane perpendicular to the plane of the periodicity.
In 2D photonic crystal structure we generally consider that the structure is infinitely extended in the third direction. But if we restrict it into finite thickness then it becomes photonic crystal slab.
Therefore my query is whether it is possible to compute its band structure in optiFDTD as it differs significantly with its 2D counterpart. If it is yes, then provide a tutorial.

• #15745
Saurav Chanda
Participant

Hey David, I have got the phc, I just need to compute the band stucture and also if I can compute band structure of a finite thickness dielectric slab waveguide.

• #15747
davcm
Participant

Hi!
Well, computing the band structure is always a solution based in a illimitated Photonic structure. And you can do it following the steps I wrote you in the previous message. If you want to know its diagram band just for a limited structure, you have to run the simulation and analyze its spectrum. There you’ll know where are the reflected bands because of your structure. I hope it is helpful for you.

Regards,
David.

• #15761
Saurav Chanda
Participant

Thanks David !!
But the photonic crystal slab situation is little bit different. It is not a 2D or 3D photonic crystal. Instead it is referred to the quasi 3D photonic crystal. Do you understand what I am trying to say? The band diagram of that slab differs significantly as compared to 2D or 3D photonic crystal. This is very important as for real systems you cant use 2D phc. It will definitely have some finite thickness in the plane perpendicular to the plane of periodicity and this thickness is the main problem to consider.
So what I need is “How to define a cell of photonic crystal slab and corresponding band diagram? Give me a tutorial.”

• #15767
davcm
Participant

Hello Saurav,
I am sorry, I can not tell you any tutorial to help you. I hope someone else can do it.

Regards,

David.

• #15836
Saurav Chanda
Participant

Hey David without any tutorial also if you can help me a bit in this regard, it would be of great help for me.

• #15897
Saurav Chanda
Participant

Hey guys, anyone please try to provide me with some data.

• #16150
Aurelien Duval
Participant

Hi,

Could you send us a small diagram or drawing of what you want to simulate? I’ll try to see if I can adapt one of our tutorials/examples for you.

Thanks

Aurelien

• #16163
Saurav Chanda
Participant

Hi Aurelien,
Yes you can check the paper “PHYSICAL REVIEW B VOLUME 60, NUMBER 8 15 AUGUST 1999”. Here I am attaching an image file, you can check it out.

Thanking you
Sourav

###### Attachments:
• #16381
Damian Marek
Participant

You can start from this project file I made (although it is a rectangular lattice instead of a hexagonal). You will notice that the reflection and transmission spectrum have peaks (or valleys) corresponding to the bandgaps.

###### Attachments:
• #16962
perveen akhter
Participant

Hi Damian,
I am also working on the same kind of structure, but your this file cannot open in fdtd 9.0. can you please upload a similar version for fdtd 9.0
thanks,
Perveen.

• #16987
Damian Marek
Participant

Hi Perveen Akhter,

I don’t have access to the older versions of OptiFDTD, so I limited to supporting our current versions of the software.

Regards

• #16965
perveen akhter
Participant

is your problem solved? what version are you using. I am trying the same kind of layout.

• #17209
perveen akhter
Participant

Hi Saurav,
did you get the photonic crystal in slab problem solved, I tried the same paper triangular lattice parameters but not getting the bandgap same as in the paper, please let me know if you were able to reproduce the bandgap from reference.
thanks,
Perveen.

• #16963
perveen akhter
Participant

here is the link of paper, I am tryig to get figure 1c
https://www.ntt-review.jp/archive/ntttechnical.php?contents=ntr200909rp1.html
also file is attached.

also I am trying to get trial version of fdtd 12, but coz my email is already on your system, its not accepting my request. can you please help me with that too. thank you very much.

###### Attachments:
• #18904
Saurav Chanda
Participant

Hello Perveen, I was busy a bit so couldn’t catch you. So what all are the problems which you are facing? You can mail me at souravchanda72@gmail.com.

Thank you