[Aurelien DuvalParticipant]

Hi, yes!

Just change the “tilting angle” setting in the “3D transverse” tab of your input plane.

Aurelien

[Aurelien DuvalParticipant]

Hi,

I just tested our email and it works fine now. Would you care to try again?

Best regards

Aurelien

[Aurelien DuvalParticipant]

Hi, you refer to OptiFDTD version 8.0 which was released in 2009.

The tutorials available online and in our current products have been updated. Please use a more recent version of the software, for example our free 32-bit OptiFDTD:

Free FDTD Download

[Aurelien DuvalParticipant]

Hi,

It’s because our files use a single column of data points (the two columns you see correspond to real and imaginary parts of the field at each point).

There’s a way to export data to a matrix format:

1) Open your f3d file using the default program (Optiwave 3D Viewer)
2) Select the desired data type (amplitude, intensity etc) in the data tab on the left so it becomes highlighted
3) Right click on the highlighted data type and select “Data viewer”
4) To export the entire matrix, click in the top-left corner of the matrix
5) Right click and select “copy selection”

You can now paste you data into excel for example.

[Aurelien DuvalParticipant]

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

[Aurelien DuvalParticipant]

Hi,

Thanks for trying OptiFDTD. A shift in resonances is likely to be due to a difference in defining the material model. We use a Lorentz-Drude fit on data from Rakic et.al “optical properties of metallic Films for vertical-cavity optoelectronic devices”, Applied Optics, Aug, 1998, Vol. 37, N0.22, pp.5272. There’s a least 4-5 sources in the litterature for gold.

Unfortunately I don’t have access to the article you mention. If you can send me a copy, I will be happy to try and see if we can reproduce the results.

Aurelien

[Aurelien DuvalParticipant]

Hi,

Sorry for the delay,

Here is your file slightly modified to include a sinusoidal grating profile. I did it for only one of the gratings, but it could be ported to the others without much problems.

I hope this helps

Best regards

Aurelien

Attachments:

1. Grating-Coupler.fdt

[Aurelien DuvalParticipant]

Hi,

You’re almost done in your example 🙂 You need to give the profile “Channel_air” a thickness. To do this:
* go to the materials and profiles designer (Edit->Profiles and materials…) and open the properties of the channel named Channel_air.
* In the 3D profile definition section, put a value in Thickness (for example 5 for 5 um), click Add
* Store the channel by clicking on the Store button (top-left corner)

If you go back to OptiFDTD_Designer, you should be able to see the cylinders in the 3D editor tab

I hope this helps

Best regards

Aurelien

[Aurelien DuvalParticipant]

Hi,

Could you send a basic drawing of your grating (with dimensions), I can try to create a project file for you.

regards

Aurelien

[Aurelien DuvalParticipant]

Hi,

Try this file.

By default, the input field is 1000 V/m, you’ll see that the light propagates across the crystal almost unperturbed. Now if you change the input field to 1 V/m (switch off the pump), then the light is steered to the other output port.

This is the expected behavior, however, I suspect a sign problem with the nonlinearities somewhere as the behavior is the inverse from the the paper!
You can try and experiment with various coefficients values and power levels.

Best regards

Attachments:

1. Thz_fast_response.fdt

[Aurelien DuvalParticipant]

Hi,

The equation ruling Kerr nonlinear materials is described in the technical background manual page 24. The values are intrinsic to the material you are trying to simulate. You can either find them experimentally or look them up in scientific articles or databases.

To change the input power:
-go to the input field properties window (by double-clicking the input source in the project browser or double clicking the red line/point in the designer window)
-Open the 2D or 3D transverse tab (depending on your type of simulation)
-Change the amplitude or power values at the bottom of the panel

Best regards

[Aurelien DuvalParticipant]

Dear Subhashish Tiwari,

I’m sorry the answers are not coming faster, we are doing the best we can. This is a community forum, so things could take a little more time. For urgent requests, please don’t hesitate to contact us directly at support@optiwave.com. We always give priority to our licensed customers.

Concerning your problem, the k-vector indexes are linked to the k-vector path which is defined in the user’s reference manual, page 76:

—
K-Vector Path area
Specifies data used to generate the k-vector point along a k-vector path in the Brillouin
zone of reciprocal lattice.
The PWE method solves all the required eigenvalues (band) based on each k-vector
point. The path is defined by set of major k-points and the associated number of
divisions along the path from one major vector to another
—

Each individual k-index correspond to a division along the k-path. If you used the predifined square ZX path, the points are as follows:

G is the k-point #0
X is a point #6 (5 divs)
M is at #10
G is at #15

It corresponds to the band diagrams definitions used in this book:
http://ab-initio.mit.edu/book/

[Aurelien DuvalParticipant]

Unfortunately you won’t be able to use this formulation with our software. You can only manipulate the epsilon tensor to some extent.

[Aurelien DuvalParticipant]

Hi,

You are right, FDTD will calculate the transmittance along the detector plane in the near-field. To account for specular transmittance you need to calculate the far-field transform (you can do this by exporting your detector plane result into f3d and then by using the far-field transform tool of the OptiTools toolbox). You can then use the far-field angular distribution to determine the power transmitted.

A similar approach was used in the following (a bit outdated) example :

Diffraction Efficiency and Diffraction Angle Based on Grating Unit Cell

To simulate an unpolarized light source, the only possibility here is to run 2 simulations:
– 1 simulation with X polarization (or TE in 2D)
– 1 simulation with Y polarization (or TM in 2D)

and then calculate the average of both simulations.

[Aurelien DuvalParticipant]

Hi,

This feature was requested a couple of times by customers. Your request will be taken into account when deciding which new features to put into the software. Thanks a lot for your input!

Best regards

Aurelien