Jones vectors for circular polarization

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Discussion Overview

The discussion revolves around the application of Jones vectors for circular polarization, specifically addressing the confusion regarding the representation of right and left circular polarization. Participants explore the mathematical formulation and implications of using a specific Jones vector.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant states that their book defines the Jones vector for right circular polarization as $$ \begin{bmatrix} 1 \\ -i \end{bmatrix} $$ but claims to arrive at left circular polarization when applying it to an electric field.
  • Another participant references Azzam and Bashara, asserting that the given Jones vector corresponds to left circular polarization and notes a missing prefactor of 1/√2.
  • A participant expresses doubt about the claim that the vector represents left circular polarization, citing multiple sources including their book and lecture notes that affirm it as right circular polarization.
  • One participant suggests that the definition of circular polarization may depend on the perspective of the observer facing the incoming wave, proposing a change in the wave's mathematical representation to maintain consistency.
  • A later reply indicates that the confusion may stem from the time-dependent nature of polarization, suggesting that the original claim of arriving at left circular polarization was a misunderstanding.

Areas of Agreement / Disagreement

Participants express differing views on whether the Jones vector $$ \begin{bmatrix} 1 \\ -i \end{bmatrix} $$ represents right or left circular polarization, with no consensus reached on the correct interpretation.

Contextual Notes

Participants note potential limitations in their understanding, including the impact of phase factors and the mathematical representation of the wave, which may affect the interpretation of polarization direction.

Decimal
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Hello, I can't seem to arrive at a result that my book states using Jones vectors for circular polarization. My book says that the unit jones vector for right circular polarization is $$ \begin{bmatrix} 1 \\ -i \end{bmatrix} $$ However when I apply this jones vector to an arbitrary electric field I arrive at left circular polarization. Here is what I did: $$ \tilde E = E_0 * \begin{bmatrix} 1 \\ -i \end{bmatrix} * e^{i(k x-\omega t)}$$ $$ \tilde E = E_0 * \begin{bmatrix} 1 \\ e^{- \frac {\pi} {2} i } \end{bmatrix} * e^{i(k x-\omega t)} $$ Applying the phase shift and rewriting: $$ \tilde E = E_0 * \begin{bmatrix} cos(kx-\omega t) \\ sin(kx-\omega t) \end{bmatrix} $$ Isn't this left circular polarized light? Where did I go wrong?
 
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Decimal said:
Hello, I can't seem to arrive at a results that my book states using Jones vectors for circular polarization. My book says that the unit jones vector for right circular polarization is $$ \begin{bmatrix} 1 \\ -i \end{bmatrix} $$

According to Azzam and Bashara [https://www.amazon.com/dp/0444870164/?tag=pfamazon01-20], your Jones vector corresponds to *left* circular polarization. (there's also a prefactor 1/√2 missing). Left-circular *lags*, because lefties are lazy laggards :)
 
Ah yes I forgot the factor. Nevertheless both my book, my lecture notes and wikipedia all state this jones vector corresponds to right circular polarization. They even state this in old exam questions. Are you sure its supposed to be left circular?
 
Decimal said:
Ah yes I forgot the factor. Nevertheless both my book, my lecture notes and wikipedia all state this jones vector corresponds to right circular polarization. They even state this in old exam questions. Are you sure its supposed to be left circular?

I guess at some point it's all relative. I think the definition corresponds to the direction of electric field rotation when you are facing the incoming plane wave, but the way I handle issues like this in class is to simply be internally consistent. So in your case, the incoming wave could be (I think) e^-i (kx-wt) rather than e^i(kx-wt) and then you are consistent... try that and see what you get.
 
Thanks for the help Andy, but I think I figured out where I went wrong. I didn't realize the polarization will of course rotate in the time ##t##. The time term in the cosine and sine is however negative, which actually inverts the sine. That's why I mixed up left and right. The polarization I arrived at in my original post was actually right circular, I just didn't realize it.
 

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