Discussion Forum

Hi

have you checked the first field in the Model emw node window: Settings: ?
There you have, I believe, the new place where to select the different wave modes

Its the same in 3D for the scattered or full mode, its in the main physics window you change the selections

One must carefully check all the entries, as many names haschanged, and the locations are placed differently, but everything, plus new physics has arrived

Good luck
Ivar

Hi, Ivar,

I am just a beginner of Comsol. And I have a question to ask you. I would appreciate it very much.

I tried to simulate dielectric scattering(an cylinder diffraction by an ideal TM plane) .

I can create ideal plane wave by setting perodice conditions on the top and bottom boundary. Left bondary is the magnetic field(set Hz=1), right boundary is the Perfect matched layer.

However, If I set the top and bottom boundary as scattering boundary condition. Left and right boundary conditions kept unchanged, it can not create a ideal TM plane wave.

How does Comsol4.0 do if I want to simulate infinite space?

Thanks in advance!

Hi

Normally you have the PML(perfectly matched Layers physics boundary conditions) to make a finite geometric volume/surface into an equivalent infinite volume, you find these under the physics tab

Good luck
Ivar

I have the same question. How can I choose TE or TM mode in COMSOL 4.0a. I searched every where I didn't find anything. I would be very thankful if somebody helps me

Best

He
for me Te or Tm are a definition isse w.r.t. a coordinate frame, So you must select the corresponding coordinate elements. i.e. in 2D and EMW you can select: three component vector, in-plane or out-of-plane. so up to you to define correctly your model and the corresponding TM TE

--
Good luck
Ivar

Ivar

Thank you for your response. In case of sending a TE or TM wave you are right I can choose my light to only have Ez or Ex and Ey. But in eigenvalue simulation when I want to find the TE modes only what should I do? I can only choose in plane or out of plane but how to differ between TE and Tm. Also I put a question about transient simulation in the forum if you can help me I will be very thankful.


Best
Faraz

I am not able to excite the hybrid mode please help me.

Do u found out how u can specify TE or TM modes?

Hi Ciccio,

Did you solve your problem? I have same problem, how to define TE or TM mode for the mode analysis? Thank you.

Best regards,

Huashun Wen

have you got the solution of this question ? if yes please help me with this i have same doubt

Ivar

Thank you for your response. In case of sending a TE or TM wave you are right I can choose my light to only have Ez or Ex and Ey. But in eigenvalue simulation when I want to find the TE modes only what should I do? I can only choose in plane or out of plane but how to differ between TE and Tm. Also I put a question about transient simulation in the forum if you can help me I will be very thankful.


Best
Faraz

Hey

When Electric field of the incident em wave is parallel to plane of incidence it is called TE mode also known as p-polarized light.
And when Electric field is perpendicular to plane of incidence , wave is called TM mode or p - polarized.

the second one is s polarized.

Hey,

sorry for my delated reply.
It's like this: the TE-like modes having the main E field component (but not only) along the x axis (parallel to the surface) and the quasi-TM or TM-like modes are referred to as Ey_mn having Ey as the major component of the E field (perpendicular to the surface).
To get a feeling for this mode behavior and the range of your effective indices you can analytically calculate the wanted effective refractive indices by ERIM (effective refractive index method) cos here you need the distinction between the two polarization states. Anyhow, before you calculated your field distribution by COMSOL you need to selected proper boundary conditions depending on what you want to know. In the Model Builder in the setting section I selected in the section “Electric field components solved for: three component vector”. This choice determines what polarizations can be handled (we want TE and TM so we need all components). Now, how to distinguish between TE an TM polarization in COMSOL?
As you can see, I solved a 2DIM waveguide with a core of 1.97, air cladding and sio2 box layer on a Si substrate. I've used Electromagnetic Waves - Frequency Domian - Mode analysis.
For plotting this field distribution I’ve selected the Ex component to plot the TE polarization and the Ey component (for the specific effective index) for the TM mode.
This is identical with the explanation before.
However, the obtained field profiles of the fundamental TE and TM modes clearly show that the fundamental TE mode is characterized by much higher field intensity at the side walls (as well as a higher refractive index), whilst the TM mode has much higher amplitude at the top and bottom interface.

many regards
susette

thanku for your response ... but i know the meaning of TE and TM modes but how to see them in COMSOL , how to detect which mode it is ??/ COMSOL RF module

Hey,

if u have understand the meaning than u should know which component is important to plot to visualize a certain polarization.
briefly and scarcely: plot Ex for TE and Ey for TM mode.

yes , thanku ....
actually i am new user to COMSOL .... so now having problem in plotting it how to select Ex or Ey????

plz explain

U select the field component (Ex or Ey) for your e.g. surface plot under "Results" "2D Plotgroup" "Electric Field" "Surface" "Expression". With the "plus" u can add the component u want.

thanku so much :-) got it ...