COMSOL - 2D axial symmetry for Light Diffraction

In summary, the conversation is about someone seeking help with simulating diffraction of optical wavelengths on a sub-wavelength aperture. They outline their goals for the simulation and explain their methods, but are struggling to get accurate results. They ask for someone to comment on their approach and potentially share their own program.
  • #1
AndrewSzelc
1
0
Hello,

I would be grateful if someone could comment on my problem.

I am trying to simulate diffraction of optical wavelength on a sub-wavelength aperture (aperture diameter/wavelength < 0.1).

What I want to achieve is:
- simulate a geometrical model with an aperture of 15um diameter
- wavelength will be varied between 10um to 200um (Parametric analysis).
- estimate what the aperture-transmitted power is as a function of the wavelength (for a fixed aperture diameter value).
- observe the diffracted wavefront (phi component and Electric field).
- understand how the polarization of the wavelength influences the transmission across the aperture cross section (can explain that further if needed).
- This means I will be increasing the wavelength and observing/reading the decreasing transmitted power.

What I did was:
- I am using RF module set for TE waves (harmonic propagation);
- 2D axial symmetry to simplify the calculations
- I drew a model of my setup in 2D axial symmetry. The geometrical model will be revolved around its axis of symmetry that is exactly in the centre of the aperture (centre of the aperture to the aperture edge = 7.5um).
- the axis of symmetry (the boundary of my geometrical model that is on the axis of symmetry) is defined as "axial symmetry" in Boundary settings.
- the remaining boundaries (apart from port) are all set for perfectly matched boundary (no reflections).
- I use "cylindrical" mode settings for emission port (I have also tried TM waves with coaxial settings, but the result was basically the same, see below).

What I get is:
- at first sight, the results seem ok as I get diffraction for "a" < lambda, but...
- the phi component of the electric field (given in V/m) is zero on the axis of revolution (axis is symmetry)
- it is as if the electric field was "disappearing" on the axis of revolution.
- That suggests that it is not a real 2D axial symmetry, since...
- I would expect the Z component to be continuous over the axis of revolution (2D axial symmetry...)

Is there anyone out there that could comment on that?
It is a very simply simulation but I cannot crack it.
All I want to do is to simulate a 2D axially symmetric model of an aperture that diffracts wavelengths.

Thanks,
Andrew
 
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  • #2
hai andrew

if you don't mind can your share your program , i am also stuck in same situation
 
  • #3
kripri1991 said:
hai andrew

if you don't mind can your share your program , i am also stuck in same situation
This person hasn't been here in 5 years, please pay attention to the date.
 

1. What is COMSOL and how is it used for 2D axial symmetry for light diffraction?

COMSOL is a software package used for modeling and simulating physical phenomena. In the context of 2D axial symmetry for light diffraction, COMSOL can be used to create a virtual environment to study how light behaves when passing through different materials or structures.

2. Why is 2D axial symmetry important in the study of light diffraction?

2D axial symmetry is important because it simplifies the modeling process by reducing the number of dimensions needed to accurately represent the system. This allows for more efficient simulations and faster results.

3. How does COMSOL account for diffraction effects in its simulations?

COMSOL uses the finite element method to solve the mathematical equations that describe diffraction. This method takes into account the behavior of light as it interacts with different materials and structures, allowing for accurate simulations of diffraction effects.

4. Can COMSOL simulate diffraction for different types of light, such as polarized or monochromatic light?

Yes, COMSOL can simulate diffraction for different types of light. The software allows for the user to specify the properties of the light, such as polarization and wavelength, to accurately model the diffraction process.

5. How can the results from a COMSOL simulation of light diffraction be used in real-world applications?

The results from a COMSOL simulation can be used to gain a better understanding of how light behaves in different situations, which can be applied to various fields such as optical engineering, material science, and medical imaging. It can also help in designing and optimizing devices that utilize diffraction, such as lenses and gratings.

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