# Modeling a wire grid polarizer.

• Niriel
In summary, the conversation discussed the speaker's work on modeling standing waves in an optical path for an astronomy spectrometer using a wire grid polarizer. The first question addressed the behavior of the x component of the electric field E when the incident wave hits the grid at different angles. The second question focused on how to effectively model the wire grid at order 0, taking into account parameters such as wire width, spacing, and resistivity. The speaker suggested using a finite element method or a specialized software program, as well as consulting existing literature and seeking advice from other experts in the field. Ultimately, it was emphasized that a combination of theoretical understanding and practical experimentation is key to finding a solution.
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.

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!

## 1. What is a wire grid polarizer?

A wire grid polarizer is a type of optical filter that selectively transmits light of a particular polarization while blocking light of other polarizations.

## 2. How does a wire grid polarizer work?

A wire grid polarizer consists of a series of parallel wires on a substrate. When light passes through the grid, the electric field of the light is either parallel or perpendicular to the wires. The component of light with the same polarization as the wires is transmitted through, while the orthogonal component is reflected.

## 3. What are the applications of wire grid polarizers?

Wire grid polarizers have a wide range of applications in optics, including LCD displays, polarizing beam splitters, and polarimeters. They are also used in scientific research for controlling the polarization of light in experiments.

## 4. How are wire grid polarizers made?

Wire grid polarizers are typically made using lithography and etching techniques to create the parallel wires on a substrate. The spacing and dimensions of the wires are carefully controlled to achieve the desired polarization properties.

## 5. What are the advantages of using wire grid polarizers?

Wire grid polarizers have several advantages over other types of polarizers, including high transmission efficiency, low absorption, and wide spectral range. They are also compact, lightweight, and can be easily integrated into optical systems.

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