How Does a Wire Grid Polarizer Work?

[semc]

This is not really a homework but I would like to confirm my understanding on the principle of a wire grid polarizer. For the polarizer to filter the polarization of EM wave, waves with e field parallel to the grid will cause the electron to oscillate in the same direction so the wave is reflected while another wave with orthogonal e field will pass through.

Is this explanation correct? If so, why does the electron movement reflect the incident wave and not radiate the wave and allows it to pass through the polarizer?

 

[voko]

Your explanation is correct.

As to why it reflects, consider that in the direction parallel to the E field, it behaves exactly like a an ordinary metallic surface behaves. Then the question is reduced to "why do metals reflect". Can you answer this question?

 

[semc]

I have no idea why metals reflect. I always thought that at the interface you have to use the continuity condition to describe the parallel and perpendicular components of the E field.

 

[voko]

The basic (classical) idea of metallic reflection is that free electrons oscillate with the frequency of incident light.

The theory works well up to the infrared frequencies. For more information, here are some keywords: Drude model; Hagen-Rubens relation.

 

[paranormal]

Your understanding of the principle of a wire grid polarizer is correct. The wire grid polarizer works by selectively reflecting or transmitting electromagnetic waves based on their polarization. This is achieved by aligning the wires in the grid in a specific orientation, which allows for the transmission of waves with a particular polarization while reflecting those with a perpendicular polarization.

In terms of the electron movement, it is important to note that the wires in the grid are very thin and closely spaced, which creates a strong electric field between them. When an electromagnetic wave with a particular polarization (parallel to the wires) interacts with this field, the electrons in the wires will oscillate in the same direction, causing the wave to be reflected. This is known as specular reflection.

On the other hand, when an electromagnetic wave with a perpendicular polarization interacts with the grid, the electric field between the wires is not strong enough to cause the electrons to oscillate in the same direction. As a result, the wave is able to pass through the grid. This is known as transmission.

So to answer your question, the electron movement reflects the incident wave because of the strong electric field between the wires in the grid, which causes the electrons to oscillate in the same direction. This reflection is a result of the specific design and alignment of the wires in the polarizer, which allows for the selective filtering of polarized waves. I hope this clarifies your understanding of the wire grid polarizer.