Quarter Wave Plates and Interference

In summary, the conversation discusses the use of quarter-wave-plates in an interference setup, where the two QWPs are opposite and will change the polarization of incoming photons. The question is which of the four cases will result in an interference pattern: 1) source emits normal light, 2) source emits laser beam, 3) source emits single photons with uncertain polarization, or 4) source emits single photons with the same known polarization. The direction of x will also play a role in the influence of the QWP on the polarization.
  • #1
protag0ras
9
0
I have a very fundamental question about interference and quarter-wave-plates. My setup contains only few elements: lightsource, QWPs, double slit and some detectors to see the interference pattern. (Detectors are missing from the bottom of the figure.)
upload_2015-1-29_13-56-24.png


An important thing is that the two QWPs are opposite so if a photon comes into QWP1 with polarization x then the QWP1 will make it left circular and if a photon comes into QWP2 with the same polarization x then the QWP2 will make it right circular.

My questions is that which of the following cases will one see an interference pattern:
1) source emits normal (not a laser) light
2) source emits laser beam
3) source emits single photons with uncertain polarization (many times)
4) source emits single photons with the same certain known polarization (many times)

Thanks in advance for any help.
 
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  • #2
Is this homework?

What do you expect in those 4 cases?

protag0ras said:
An important thing is that the two QWPs are opposite so if a photon comes into QWP1 with polarization x then the QWP1 will make it left circular and if a photon comes into QWP2 with the same polarization x then the QWP2 will make it right circular.
Note that this will require a specific direction of x (depending on the orientation of the optical axes in the QWP). In particular, there are other directions that will not be influenced by the QWP at all.
 

1. What is a quarter wave plate?

A quarter wave plate is an optical device that is used to modify the polarization of light. It consists of a thin layer of birefringent material that is typically made of quartz or mica. When light passes through a quarter wave plate, its polarization is changed to a specific angle depending on the thickness and refractive index of the material.

2. How does a quarter wave plate work?

A quarter wave plate works by exploiting the principle of birefringence in materials. Birefringence is the property of certain materials to have two different refractive indices for light traveling in different directions. When light passes through a quarter wave plate, one of the refractive indices will slow down the light by a quarter of a wavelength, while the other will not. This results in a phase shift between the two components of the light, which leads to a change in polarization.

3. What is the difference between a quarter wave plate and a half wave plate?

The main difference between a quarter wave plate and a half wave plate is the amount of phase shift that occurs between the two components of light passing through them. A quarter wave plate causes a phase shift of 90 degrees, while a half wave plate causes a phase shift of 180 degrees. This means that a quarter wave plate can convert linearly polarized light into circularly polarized light, while a half wave plate can convert circularly polarized light into linearly polarized light.

4. How is a quarter wave plate used in interference experiments?

In interference experiments, a quarter wave plate is used to manipulate the polarization of light so that it can interfere with itself. This is achieved by placing the quarter wave plate between a polarizer and a beam splitter. The polarizer filters the light to a specific polarization, and the quarter wave plate converts it to a different polarization. When the two beams of light recombine at the beam splitter, they interfere with each other, producing an interference pattern that can be observed.

5. What are some practical applications of quarter wave plates?

Quarter wave plates have several practical applications in optics and photonics. They are commonly used in optical communication systems to manipulate the polarization of light signals. They are also used in polarimeters to measure the rotation of polarized light by certain substances. Additionally, quarter wave plates are used in optical devices such as LCD screens and 3D glasses to control the polarization of light for better image quality and viewing experience.

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