Discussion Forum

Hi,

I can tell you that everything works in version 4.3 and the program handling is much more effective than it was in 3.5. It is very different though, and it takes some time to find through. Maybe the community can help you, but you will need to be more specific about your model.

Cheers
Edgar
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Edgar J. Kaiser
www.emphys.com

Thanks a lots for your answer,


I have a small query regarding the above issues.

i want to simulate a system having periodic nanostructures placed in substrate of complex refractive index also calculate the reflection and transmission coefficient at top and bottom layer in visible range. for that i need to define port , and also appropriate PML layer which will takes care of all unwanted reflection and transmission from the structures. now i am attaching my simulation model in the attachment file.

step followed for simulating my model as below
1. Define all parameter and also built the geometry. here also I am facing problem for uploading the txt file for defining material properties (real and imaginary part of refractive index) through interpolation function.

2. Define the PML layer and identity pair at top and bottom layer.

3. While define the plane wave as the excitation source at the identity pair which is the interface of air top surface and bottom surface of PML layer1 , but it was not taking in the option menu. Could you suggest me what will do for this. currently I am using Comsol 4.3 version, earlier in 3.5 it had been taken in nice way but 4.3 version i dont know where is the mistake.

Here i have attached my model below.

The picture looks reasonable but it doesn't tell what might be wrong in the model.

How are you treating the lateral boundaries? You may need a periodic BC there.

Cheers
Edgar

--
Edgar J. Kaiser
www.emphys.com

Gangadhar,

Seems, you are using Form Assembly + PML options to avoid back reflection from the exciting port. This is old approach used in version 3.5. In Comsol 4, different approach is used which doesn’t require assembly and identity pairs. Generally, you almost never need to use Form Assembly option anymore in RF Comsol 4 version. The approach to solve grating type problem in new version is illustrated in the following example model
www.comsol.com/showroom/documentation/model/10032/

Steps to upload real and imaginary parts of the refractive index are described in the following example model:
www.comsol.com/showroom/gallery/12415/

Regards,
Sergei

Thanks a lot dear sir giving me valuable suggestion for me.

Dear friends,

define the propagation vectors in a multilayer system.

i have attached the simulation detail in the attachment . somebody help me out to solve this problem

Aim: To find out the reflectance and transmittance , nano disc on dispersive layer.
I have define all the parameters as earlier support.
The result what i am getting is not upto my certification. i dont know where i made the mistake while doing the simulation.


I have a series of question regarding my simulation.
1. Variable part : In my domain i have used silicon which is a dispersive material, for that i have used the interpolation function and upload the txt file. it was work nice, my question is how will check whether my data is taking at time of simulation or not.
2. Regarding the define the wave vector and propagation constant in the variable domain.
here i have used a multilayer system, at each interface the wave vector and angle of incidence get changed , my question is i need to define the propagation constant at each interface as i have defined the port at the extreme interface of my domain.
as i know for a multilayer system obey snell law, so
n_air*sin(theta1)=n_2*sin(theta2)=n_3*sin(theta3)
now sin(theta3)=asin(sin(theta1*(n_air/re(n_2)))
after that i have defined as respective propagation vectors
k1x=emw.k0*sin(theta1), kaz=emwk0*cos(theta1) this is defined at the excitation port 1
exciation field
Ey= exp(-i*k1x*x)[V/m], propagation constant= abs(k1z)
Similarly in other port 2
k4x=emw.k0*sin(theta3)*re(n_2), k4z= emw.k0*cos(theta3)*re(n_2)
Ey= exp(-i*k4x*x)[V/m], propagation consatnt= abs(k4z)
PBC and PEC Bounadry condtion chosen at necessary interface.
in between i have not defined any thing , could you suggest me my parameter setting is wright or wrong.
For meshing
i have chosen gold dsin mesh size 20nm maximum 10nm minimum.
for Silica 20nm max ans 10nm min.
silicon 40nm max mesh and 10nm min.
when i go for smaller mesh size that 5nm -10nm , my computer has been hanged. (computer memory 8gb ram, 500gb hard dsic, 64bit window7 operating system
also choose the direct solver in the default setting

after that i have defined all parameter perfectly, i have mesh it also as you suggest earlier.
i have simulate it, its run without sending any message, but the result i got not satisfactory.
i have attaching the result which 50nm inter spacing , i also try for small step size in parameter sweep , the result is shown like oscillatory up and down. the reflectance(R) and transmittance(T) absorption(A) vs wavelength as shown below


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akash