Modeling a wire grid polarizer.

[Niriel]

Hello,

I keep myself busy by trying to model/predict standing waves in the optical path of a heterodyne spectrometer we built in our lab.

We split and combine the local oscillator and the sky (it's for astronomy) with a beam splitter. Our beam splitters are wire grid polarizers.

The Idea is simple: if our wire grid is in the (y;z) plane, with the wires along the z axis, then:

• the z component of the electric field E of the incident wave is reflected
• and the y component passes through.

Therefore we split the incoming beam into two linearly polarized beams.

First question:

What happens to the x component of E ? E does have a component along x since the TEM wave can hit the grid at any angle.

Second question:

Modeling the grid at order 0 is trivial: just set up a matrix for a 4-port device with zeros and ones in it for each polarization. But reality is not that simple, and I need to include parameters such as the width of the wires, their spacing, and the resistivity of their metal. Also, I need to keep the phase information.

How would you approach the problem ? I imagine that there is something smarter to do than brute-forcing Maxwell. :yuck:

 

[eljose79]

Hello,

It's great to hear about your work on modeling standing waves in an optical path for an astronomy spectrometer. This is a very interesting topic and I appreciate your enthusiasm for it. To answer your first question, the x component of the electric field E will depend on the angle at which the TEM wave hits the grid. If the incident wave is at an angle other than 0 degrees, then there will be a component of E along the x axis. This component will also change as the angle of incidence changes.

For your second question, there are a few different approaches you could take to model the grid at order 0. One option could be to use a finite element method (FEM) to solve Maxwell's equations for the grid structure. This would allow you to include parameters such as wire width, spacing, and resistivity, as well as keep track of the phase information. Another approach could be to use a software package that specializes in simulating optical systems, such as Zemax or Comsol. These programs have built-in tools for modeling and analyzing wire grid polarizers.

In terms of finding a smarter way to approach the problem, I would suggest looking into existing literature and research on wire grid polarizers and their properties. This could give you some insights into different modeling techniques and approaches that have been used in the past. Additionally, consulting with other experts in the field or attending conferences and workshops may also provide valuable insights and ideas for your research.

Overall, I think it's important to approach the problem with a combination of theoretical understanding and practical experimentation. Good luck with your research and I look forward to hearing about your progress!