i want to know, do comsol FDTD method for simulation spectral thermal radiation in subwavelength .However, beware that the time solver is not in the best equipped form. Lack of PMLs and any built-in support for metals

]]>You may find this article helpful:

https://www.comsol.com/blogs/using-perfectly-matched-layers-and-scattering-boundary-conditions-for-wave-electromagnetics-problems/

As for time-domain modeling, for this you will currently want to use the absorbing BC. ]]>

Does anybody knows how to set perfectly matched layer (PML) in boundary condition in electromagnetic wave time domain (teew)

]]>Well by looking at your post I tried to create a model which calculate the transmission through periodic structure which is fabricated on ITO coated glass substrate.

I have used periodic port to ensure that it would capture the information about all diffraction order.

Also I have used the concept of Frequency selctive model from RF module. I have some doubt in this model why there Port type is Domain-backed and orientation is Reverse.

The appropriate place to ask such questions would be of your COMSOL Support Team: http://www.comsol.com/support/

]]>From last 6 months, I have been trying to learn COMSOL Multiphysics. I couldn’t find anyone to discuss my doubts while doing the tutorials for Plasmonic wire grating and FSS , split ring resonator. I finally found this blog where periodic structure is discussed as my work is also on periodic structures. Writing my questions here hoping that would be answered by you or anyone who will read this.

While going through the FSS/Split ring resonator I have following doubts:

1) the (1) emw.k0*sin(theta)*cos(phi) (2) emw.k0*sin(theta)*sin(phi) (3) emw.k0*cos(phi) are put in variables. Can we write them in parameters? And I think these components determine the direction of incident of light.

2)Difference between domain backed and PEC slit type. What actually their functions are and how would they affect the simulation?

3)Port orientation is been taken as reverse for both ports 1 and 2. Why? And the directions of the arrow of the port is same whether I click it for forward or reverse. What does it make difference?

4) While defining the properties of port, input quantity is given as magnetic field. Why it is magnetic field, can’t we put electric field as a input quantity ? And also exp(-i*k_x*x)*exp(-i*k_y*y) j A/m is given for the mode, it means wave is traveling in XY plane K has both the component kx and ky and the direction of magnetic field is along y direction. but magnetic field should be perpendicular to direction of propagation.

4) again if wave is propagating in XY plane than how the propagation constant beta = abs(k_z)?

5) Since both plasmonic wire and FSS are periodic structure then why port periodicity is considered in former one not in later one?

I am lost. Please help me out.

Thanks

Kalpana

http://www.comsol.com/model/10032 (RF Module)

http://www.comsol.com/model/14705 (Wave Optics Module, same example)

This demonstrates the diffraction orders (in 2D)

In 3D:

http://www.comsol.com/model/frequency-selective-surface-periodic-complementary-split-ring-resonators-15711

http://www.comsol.com/model/modeling-of-pyramidal-absorbers-for-an-anechoic-chamber-12129

http://www.comsol.com/model/fresnel-equations-12407

These demonstrate Floquet periodicity, but without the computation of diffraction orders.

Can anyone help me How to use Floquet boundary condition in case of 3d structure. I want to simulate a model which calculate scattering through array of nanodisc which lie on XY plane .. say i am supposed to incident an electric field through z- axis polarization along either x or y. So in that case what should be my floquet boundary condition??

]]>Right now the plasmonic wire grating example is the best place to get started: http://www.comsol.com/model/10032

And we are working on some other models as well.

Best,

Walter ]]>

If you have some example models it would be great to see (.mph as an example).

Thanks in advance!

Illia Fedorin.

]]>Can you help me in this regard?

I would like to find the electric filed intensity of reflection(or reflectance) from gold nano pillars from gold substrate, with the consideration of diffraction orders in case of reflection((1,1 ), (1,0 )reflection grating orders), for the different wave lengths starting from 200 nm to 1000 nm, for a fixed angle of incidence (normal incidence, or 30 degree angle of incidence)

I had made a 2D grating structures in 3D modeling Wizard of Comsol 4.4 version, While I am putting Diffraction orders( m=0, n=0 ; m=-1, n=0 ; m=+1, n=0) with “port reference points” as diagonally opposite end of Unit square cell with periodic boundary conditions on all four sides( by doing copay face). Unfortunately it gives me zero electric filed while i am running., If I run the same model without diffraction order it gives the result but only from one order diffraction (normal reflection) . Since I need to calculate reflection from at least two orders (0 th order and 1 st order) I have to include those diffraction orders to my model

Can you help me in this regard?

can you tell me how to put diffraction orders (with proper port reference points)in 2d grating on 3D model?

Also How can i implement PML layer over the port ( or it is really needed ), since if i add PMLl layer on the top of port, selecting port reference point is declined by default. I follow the pyramidal absorption model for making the infinite array of my 2d Grating nano structures( there a PML layer added over the port)

the plasmonic wire grating model available in Comsol library is just a 2D model , so we can’t able to follow the same thing in here in our model.

I used this blog for making port reference points and putting periodic ports

http://www.comsol.co.in/blogs/modeling-electromagnetic-waves-periodic-structures/

Please help me in this regard..

Thank you

Aneesh M Joseph

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