Questions tagged [polarization]

Polarization characterizes the oscillations in time the electromagnetic field is doing in the plane perpendicular to the propagation direction of a wave

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Peskin & Schroeder Chapter 16.1 derivation

I am trying to derive the term shown in chapter 16.1 in Peskin & Schroeder. We have defined our polarisation vectors as $$ \epsilon^+_\mu(k)=\left(\frac{k^0}{\sqrt{2}|\vec{k}|},\frac{\vec{k}}{\...
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Polarization vector basis in Peskin & Schroeder

I am studying chapter 16.1 of Peskin & Schroeder and I am trying to understand how the chosen polarization vector basis works. It is given by the following: $$ \epsilon_i^T\cdot\epsilon_j^{*T}=-\...
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What axis should we consider in a double polarizer?

Q : Unpolarized light of intensity I passes through an ideal polarizer A. Another identical polarizer B is placed behind A. The intensity of light beyond B is found to be I/2. Now another identical ...
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How to understand the polarization rotator using a PBS, a quarter-wave plate, and a mirror?

In optics experiments, I often see the following optics configuration to rotate the polarization of an incident linearly-polarized laser beam. The final reflected beam has its polarization rotated by ...
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Why is $\mathcal{M}(k)$ given by this? (Ward Identity derivation in Peskin & Schroeder)

In page 160 of Peskin & Schroeder we are considering an amplitude $\mathcal{M}(k)$ with an external photon as given in equation (5.77) $$ \sum_{\epsilon}|\epsilon_\mu^*(k)\mathcal{M}^\mu(k)|^2=|\...
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Photon polarization with respect to quantization axis

I really struggle to understand $\pi$, $\sigma^{\pm}$ transitions. I am aware that I need a quantization axis to define my angular momentum levels $m_z = \pm\hbar m$. I am also aware that $\Delta m = ...
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Different wave speeds when considering direction of electric or magnetic field in birefrigent materials

Let us consider a linear birefringent material which is not isotropic and has three principal axes with refractive indices $n_1$, $n_2$ and $n_3$ for the $x$, $y$ and $z$ directions, respectively (we ...
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Choosing the polarization vectors, Quantization of EM field

In Sakurai, Modern Quantum Mechanics 3rd edition, page 465, the book writes: The set of solutions to $$\nabla^2\boldsymbol{A}-\frac{1}{c^2}\frac{\partial^2\boldsymbol{A}}{\partial t^2}=0\;\;\;\;\;\;\;\...
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For unpolarized plane wave traveling normal incident from air to dielectric what are the reflection and transmission coefficients?

Given an unpolarized plane wave traveling in air and hitting a dielectric at normal incident what equations can be used to calculate the reflection and transmission coefficient? I know for a polarized ...
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Intensity of circularly polarized EM wave after linear polarizer

When a circularly electromagnetic wave is normally incident on a linear polarizer, what are the properties of the output wave? From what I understand, it will be a plane EM wave, but what about the ...
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Why Does an Electric Field Arise In This Situation?

Suppose you have a battery, and using some wire you connect the positive terminal of the battery to some conductive piece of metal (i.e. an electrode) and similarly you connect the negative terminal ...
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Elliptical polarisation - unsure as to what quantity is on wikipedia page

quick question - https://en.wikipedia.org/wiki/Elliptical_polarization - what is $\alpha_{x}$ and $\alpha_{y}$? It's not defined on the page. I'm asking to answer part of a question, which requires me ...
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Real and Imaginary part for particle polarisability

I am trying to determine the real and imaginary parts from the following equation for the polarisability of particles $\Lambda_{MG}(\lambda)$: $$\Lambda_{MG}(\lambda) = \frac{\epsilon(\lambda) - \...
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How to convert from plus and cross polarization modes ($h_{+}$, $h_{×}$) to spin-weighted spherical harmonic $h_{lm}$?

I was wondering if there is a method to express the $h_{+}$ & $h_{×}$ polarization modes to spin-weighted spherical harmonic $h_{lm}$. I ask this in the context of gravitational waves. We see that ...
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Vector potential of photon in quantum field theory

In quantum field theory the solution to Maxwell's equation is given by: $$ A^\mu(x)=\underbrace{\sum_{r,\mathbf k}\frac{1}{\sqrt{2V\omega_{\mathbf k}}}\varepsilon_r^\mu(\mathbf k)a_r(\mathbf k)e^{-ikx}...
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Two different types of circularly polarized light

Circularly polarized light [$\mathbf{E}=E_0e^{-i\omega t}(\hat{x}+i\hat{y})$] usually refers to the light whose propagation direction is perpendicular to the polarization plane, like this figure on ...
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Can I use all 4 sides of a polarizing beamsplitter cube as inputs?

The polarizing beamsplitter cube on the following diagram splits non-polarized light in the input a into 2 orthogonal polarizations: p-polarized light is transmitted into the output c while s-...
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Non-polarizing beamsplitter and polarized light source

I have a non-polarizing BS and a polarized source (linear horizontal). What polarization states should I observe on the output? My intuition is that, since a non-polarizing BS is just a half-mirror, ...
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Why wire grid polarizers do not re emit absorbed radiation both ways?

The wikipedia page on polarizers states about wire grid polarizers that : "Electromagnetic waves that have a component of their electric fields aligned parallel to the wires will induce the ...
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Can a polarized light be reflected?

First of all, this question is NOT about what happens to an unpolarized light when it is reflected by a surface. This question is already well answered by the web and is not my current concern. I am ...
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Virtual Graviton Polarisations

Is it true that in canonically quantised gravity "non-traceless" and "non-transverse" gravitons are allowed to exist as virtual particles, whereas any graviton that corresponds to ...
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How does reflection polarise light on the atomic level?

From my reading when light is reflected S-p polarisation occurs with the reflected light being parallel to the surface in polarisation and the mixed light being transmitted through. Light is absorbed, ...
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What is the gravitational lensing impact on polarity?

Gravitational lens is known for light bending, and gravitation can impact its frequency, but does it any impact on the polarity of this light?
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How does an attenuator inside a polarization interferometer change polarization?

Suppose you have source of coherent light, a laser beam, with +45 polarization. A polarizing beam splitter (PBS) splits the beam into its horizontal and vertical components. The second polarizing beam ...
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How to implement a very precise polarizer inside a fiber-based setup?

A tricky question: I need to use polarizers with a ~5 arcmin precision inside a PM fiber-based system. What are some (hopefully cost-effective) ways of achieving this? The setup works with linear ...
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Combination of three polarizing filters which (in any order) completely block transmission, such that no two filters do so

A pair of ideal linear polarizing filters, oriented perpendicular to each other, will be opaque despite the fact that each filter individually only blocks 50% of the light. I would like to extend this ...
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Refractive Index Ellipsoid for Circular Birefringence Materials

When light travels through an anisotropic medium, its refraction may depend on both its polarization and propagation. Such materials may be classified in terms of their (Linear) Birefringence as ...
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Charges densities and boundaries conditions for an non-linear dielectric sphere

If an non-linear dielectric sphere is not charged and $\vec{P} = P\hat{z}$ does it means that $\rho_f$ = $\sigma_f = 0$ and that $\rho_b = -\nabla \cdot \vec{P} = 0$ since $\vec{P}$ is a constant. ...
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Momentum Conserving Delta Function and Soft Gravitons

I am reading a paper called "Testing subleading multiple soft graviton theorem for CHY prescription" written by Subhroneel Chakrabarti, Sitender Pratap Kashyap, Biswajit Sahoo, Ashoke Sena ...
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Complex electric field in second order polarization

I am reading an introductory article on nonlinear optics. Here is what the part that's troubling me says: $$\tilde E(t) = Ee^{-i\omega t} + \text{c.c} $$ When this electric field is incident on a ...
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Finding explicit forms of two polarization vectors of massless spin-1 particle

I have trouble with solving Problem 8.5 (c) from Schwartz QFT book. The problem is about finding explicit forms for the two polarizations, which are orthogonal to the momentum vector $p^\mu$ and an ...
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Completeness relation of Polarisation tensors

I was studying certain topics related to asymptotic symmetries and soft theorems and was mainly looking at "Lectures on Infrared Structure of gauge theories and gravity" By Strominger (https:...
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Electric dipole approximation for perturbation: What is this symbol and how was it part of this derivation?

I'm reading electrodynamics physics notes that describe the polarization of a medium. The notes describe the active atoms as having two levels $a$ and $b$, separated by energy $\hbar \omega$ and ...
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Why is vacuum polarisation diagrams called like this?

I have read about the vacuum polarisation diagrams e.g. for the photon propagator, but I don't understand why it is called "vacuum polarisation". Can it be interpreted as an interaction of ...
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What are the real Electromagnetic fields of Circularly Polarized Light?

It is my understanding that the $\vec{E}$ and $\vec{B}$ fields of a circularly polarized photon sit purely in the $(1,0)$ or $(0,1)$ representation of the (complexified) Lorentz Group, and have ...
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How can we extrapolate gravitational waves in the early universe from CMBR?

I know it has to do with polarization of CMBR, but not sure how gravitational wave polarized early light.
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Is it possible to produce circularly polarized gravitational wave and how to determine if it is CW or CCW?

I saw the GIFs showing both "plus" and "cross" linearly polarized gravitational wave using ring of dots, how about circularly polarized gravitational wave, if so how are they ...
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Do noble gases attract each other?

When 2 atoms come close enough, the nucleus and the electron cloud attract each other, the electron clouds are pulled between the the nuclei's until an equilibrium distance is reached. Why doesn't ...
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Why is circularly polarized light used for optical pumping?

Why not linearly polarized light or unpolarized light? Maybe I've misunderstood atom-light interactions, but I thought that an electromagnetic wave with the right energy incident on an electron ...
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Experimental data for polarization of electrons at double slits

What are the results of experiments with electrons deflected by obstacles? More in detail, what is the direction of the magnetic dipole of the electron with respect to the edge of the obstacle?
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What percentage of photons pass through a polarization filter?

Assuming all photons have random states, what percentage of photons make it through a polarization filter with preferred axis $\newcommand{\bra}[1]{\left<#1\right|}\newcommand{\ket}[1]{\left|#1\...
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Polarization and Magnetization analogy

In (linear, isotropic, homogeneous) matter, an externally applied E field $E_{ext}$ will induce polarization $P = \epsilon_{0} \chi_{e} E$ which then produces its own E field $E_{bound} = -P/ \...
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Free, bound and total charge density

If in a medium we have: $\rho(\vec r)_{total} = \rho(\vec r)_{free} + \rho(\vec r)_{bound} $. Now we know: $-\nabla\vec P = \rho(\vec r)_{bound}$ $\nabla\vec D = \rho(\vec r)_{free}$. Since $\vec D=\...
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What happens to other states of polarized light than $s$ or $p$ when encountering a filter/surface?

I'm trying to understand Brewster's angle and am stuck on what the different types of polarization actually mean (I'm a total beginner in physics so I might have misunderstood some very basic concepts)...
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What is an example of experimental confirmation of Fresnel equations?

I have been reading about Fresnel equations, but I am struggling to find a single experiment where it was experimentally demonstrated that indeed polarised light follows the function predicted by ...
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Averaging over spin phase-space for a cross section

In Peskin and Schroeder the Dirac equation is solved in the rest frame for solutions with positive frequency: $$\psi(x) = u(p) e^{-ip\cdot x}$$ $$u(p_0) = \sqrt{m} \begin{pmatrix} \xi \\ \xi \end{...
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Polarization of natural light for double slit interference

Last week I performed Young's double slit experiment using a laser. As expected, I obtained an interference pattern as predicted by Fraunhofer theory (enveloped by the 1 slit diffraction curve). Then, ...
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Is a linearly polarized plane wave a scalar wave?

A linearly polarized plane wave, say polarized along the x-axis, in a homogeneous medium has its electric field given by $$\mathbf E(x,y,z) = (A e^{ik(ay+bz)}, \ 0 \ , \ 0)$$ where $A,a,b$ are real ...
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Can you make polarizing filters out of non-conductive materials?

I have seen it said that Faraday cages and wire grid polarizers work because they are conductive, and light oriented along the slits will activate the motion of electrons that will then block the ...
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Relationship between $\vec E$,$\vec P$,$\vec D$ inside a dielectric material

If we put a dielectric material in region where an electric field $\vec E_0$ is present then, the fields that are present within the dielectric are: $\vec E$,$\vec P$,$\vec D$ . $\vec E$ is the ...
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