What is Polarization: Definition and 660 Discussions
Polarization (also polarisation) is a property applying to transverse waves that specifies the geometrical orientation of the oscillations. In a transverse wave, the direction of the oscillation is perpendicular to the direction of motion of the wave. A simple example of a polarized transverse wave is vibrations traveling along a taut string (see image); for example, in a musical instrument like a guitar string. Depending on how the string is plucked, the vibrations can be in a vertical direction, horizontal direction, or at any angle perpendicular to the string. In contrast, in longitudinal waves, such as sound waves in a liquid or gas, the displacement of the particles in the oscillation is always in the direction of propagation, so these waves do not exhibit polarization. Transverse waves that exhibit polarization include electromagnetic waves such as light and radio waves, gravitational waves, and transverse sound waves (shear waves) in solids.
An electromagnetic wave such as light consists of a coupled oscillating electric field and magnetic field which are always perpendicular to each other; by convention, the "polarization" of electromagnetic waves refers to the direction of the electric field. In linear polarization, the fields oscillate in a single direction. In circular or elliptical polarization, the fields rotate at a constant rate in a plane as the wave travels. The rotation can have two possible directions; if the fields rotate in a right hand sense with respect to the direction of wave travel, it is called right circular polarization, while if the fields rotate in a left hand sense, it is called left circular polarization.
Light or other electromagnetic radiation from many sources, such as the sun, flames, and incandescent lamps, consists of short wave trains with an equal mixture of polarizations; this is called unpolarized light. Polarized light can be produced by passing unpolarized light through a polarizer, which allows waves of only one polarization to pass through. The most common optical materials do not affect the polarization of light, however, some materials—those that exhibit birefringence, dichroism, or optical activity—affect light differently depending on its polarization. Some of these are used to make polarizing filters. Light is also partially polarized when it reflects from a surface.
According to quantum mechanics, electromagnetic waves can also be viewed as streams of particles called photons. When viewed in this way, the polarization of an electromagnetic wave is determined by a quantum mechanical property of photons called their spin. A photon has one of two possible spins: it can either spin in a right hand sense or a left hand sense about its direction of travel. Circularly polarized electromagnetic waves are composed of photons with only one type of spin, either right- or left-hand. Linearly polarized waves consist of photons that are in a superposition of right and left circularly polarized states, with equal amplitude and phases synchronized to give oscillation in a plane.Polarization is an important parameter in areas of science dealing with transverse waves, such as optics, seismology, radio, and microwaves. Especially impacted are technologies such as lasers, wireless and optical fiber telecommunications, and radar.
Figure from Jackson, the ##0## subscripts indicate incident waves whereas the lack of subscripts indicate the scattered wave.
Figure from Zangwill, the hat ##\hat{e}## vectors are for the incident electric field. We are dealing with unpolarized light so we have two orthogonal polarization...
I guess I will show my work for substantiating equation 1 and hopefully by doing so someone will be able to point out where I could generalize.
##\langle \vec{S}_{rad} \rangle = \frac{1}{2 \mu} \mathfrak{R} \left( \vec{E}_{rad} \times \vec{B}^*_{rad}\right) = \frac{1}{2 \mu} \mathfrak{R} \left(...
Summary:: A plane wave incident upon a planar surface - determining polarization, angle of incidence etc.
𝐄̃i = 𝐲̂20𝑒−𝑗(3𝑥+4𝑧) [V. m−1 ]
is incident upon the planar surface of a dielectric material, with εr = 4, occupying the halfspace z ≥ 0.
a) What is the polarisation of the incident wave...
Hello everyone,
I've got my non-uniform electric cloud distribution formula given by:
## \rho(r) = \frac {-Ze} {\pi a^3} e^{-{2r}/a}##
Where ##Z## is the atomic number of the atom in question and ##a## Bohr's radius and ##E_L## the local electric field.
Considering the previus expression ...
In Griffiths Elementary Particles (2nd, revised edition) there is a footnote on page 241, which states that the photon states with ##m_s = \pm 1## are related to the polarization vector by:
$$\epsilon_+ = \frac 1 {\sqrt 2} (-1, -i, 0) \ \text{and} \ \epsilon_- = \frac 1 {\sqrt 2} (1, -i, 0)$$...
If I have three modes in an optical fiber with elliptical facet as shown in the figure, what would be the polarization direction of the modes... what I know that it is linear polarization and could have several configuration.. but what I want really to know that if could be a situation where the...
I was trying to research about polarizing lasers for an experiment, and there were some things that were confusing? A website said,
I was wondering if the polarization ratio was the same as the extinction ratio?
Also, I was curious because I thought 100:1 would be a lot, and not much light...
Hi, this is not an exercise. In some lecture notes the authors states that from elementary EM I should familiar with the fact that the work associated with polarization and magnetization of a material is given by ##\delta W = E dP## and ##\delta W = BdM##. I have to admit that I am super rusty...
The equation above (from Wikipedia), assumed that the Gaussain beam has polarization in x-direction, as I know that the polarization means that the oscillation direction of the electric field and so the intenisty... so how we get circular intensity in every direction which means in x and y...
Looked upon this and can't seem to find anything.
The formula I=Icos^2theta seems to only work for polarization filters, which is not this case.
On the other hand, the brewster's angle only c.aclates the angle when the REFLECTED light is polarized, not the REFRACTED light.
Hence I am confused...
I'm looking forward to have a better understanding of the polarization vector in quantum field theory in order to solve a particular problem.
In class and in several textbooks I see that ##s^\mu=(0,\vec s)## and ##|\vec s|=1##. Are polarizations vectors defined to have no temporal component in...
I don't even know where to start with this problem. What kind of slit makes linearly polarized light circularly polarized?
The correct answer is d = lambda/(4(n1 - n2)) = 856nm. But how do I get there?
Thanks in beforehand!
Hi!
As I outlined in my https://www.physicsforums.com/threads/hello-reality-anyone-familiar-with-the-davisson-germer-experiment.985063/post-6305937, I'm curious to ask if there is anyone with knowledge on the theory of the piezoelectric effect on this forum? I think it's fascinating how a...
The following is a diagram of an EPR thought experiment using photons that uses the same type of components as described in this paper http://www2.optics.rochester.edu/~stroud/cqi/rochester/UR19.pdf
Would you detect any photons at the right detector?
I want to be convinced one way or another...
I am struggling to get my work to match the posted solutions to this problem. I understand part (a) but can’t get the integral to work out for (b). I know I have to use Biot-Savart and add up the components from the the surface and volume currents. The cylinder is very long, so I need to make a...
If a laser beam has a definite diagonal polarization, it is in a superposition of horizontal and vertical polarization. If that beam were then sent through another lasing medium and caused stimulated emission of another photon (or possibly several photons), would those be in superposition...
I set up the equation
.5((cos 12)^2)^x = 1/9
Solving for x gets me 34.037
34 + 1 = 35
I've entered answers of both 34 and 35 and both have been marked as wrong. Does anybody know what I'm doing wrong here?
I'm a high school teacher. In the curriculum, students are required to explain that polarization of light shows that light is a transverse wave.
My answer: In order to explain polarization, we have to consider the electric field vibration direction. For example, on a wave that propagates...
Hello,
I'm trying to obtain a polarization curve for a fuel cell (two electrodes in HCl). From what I've seen in literatures, current is applied and the voltage is measured. Is it still the same to change the voltage and measure the current instead? For some reason our equipment only have the...
Hello,
If I have a quadratic form ##q## on a ##\mathbb{R}## vectorial space ##E##, its associated bilinear symmetric form ##b## can be deduce by the following formula : ##b(., .) = \frac{q(. + .) - q(.) - q(.)}{2}##. So that, an homogeneous polynomial of degree 2 can be associated to a blinear...
Two waves are linearly polarized. The electric field of one wave is aligned with the x-axis and the other is aligned with the y-axis. In the absence of matter that might change the polarization, can these waves interfere with each other?
I spent a good amount of time thinking about it and in the end I gave up and asked to a friend of mine. He said it's a 1-line-proof: just "integrate by parts" and that's it. I'm not sure you can do that, so instead I tried using the identity:
to express the first term on the right-hand side...
So, I was in class listening to my lecturer when I notice something intriguing. I was looking at the reflection of a lamp on the screen of my calculator. I paid close attention to the colour of the light reflected of my calculator and realized that when I rotate my calculator by about 90 deg...
Hello.
Recently we began taking static electricity and our teacher asked us to do a research paper on static electricity and charges in general to help us understand the material better. I've been stuck a bit on trying to understand what's the difference between polarization and induction and...
This text
https://en.wikipedia.org/wiki/Photon_polarization
starts with:
"Photon polarization is the quantum mechanical description of the classical polarized sinusoidal plane electromagnetic wave. An individual photon can be described as having right or left circular polarization, or a...
In Griffith's "Introduction to Electrodynamics" says that in a bar electret the curl of the polarization does not equal zero everywhere. Why is that ? Thanks in advance
I want to understand the concept of polarization of light. I would like someone to clarify how I am thinking about it:
If light is a transverse wave and it is basically an electric field(E) and magnetic field(B) each oscillating in different directions (axes) which are perpendicular to each...
I think I can write the density matrix as $$\rho = \frac{1}{2} ( |R \rangle \langle R | + |L \rangle \langle L | ).$$ The state of a linear polarized light in the direction ##\textbf{a}## can be write as $$|\theta \rangle = \frac{1}{\sqrt{2}} ( e^{-i \theta} |R\rangle + e^{i \theta} |L\rangle...
Hi everyone,
When an electromagnetic wave passes through a material, then depending upon the atomic structure of that material it polarizes that material. There is another definition of polarization in physics which says that polarization is the direction of oscillating electric field in EM...
I've seen this video:
There it is explained that an electromagnetic (here radio) wave has a phase shift if it was radiated in horizontal polarization, but it does not experience the phase shift when it was emitted vertically polarized when it gets reflected on the ground.
When reading up on...
Homework Statement
I am doing an assignment on Polarization of light. I have conducted experiments to prove that reflected light is at least partially plane-polarized, and to prove that Malus' Law is true. Both my experiments have given good results. I now need to find enough stuff to write...
I understand how polarization can be explained using EM waves. However, I am unable to understand how to explain how polarization filters work when we use the concept of photon spins. Can someone help me with that?
Hi all,
I'm trying to understand how to describe the quantum state of entangled photons, including their phase, if one of them encounters a double-slit.
Here's a simple example:
Suppose you have two polarization-entangled photons A and B in the following Bell state:
\begin{equation}...
Homework Statement
Suppose two polarization-entangled photons A and B in the following Bell state:
\begin{equation}
\Phi=\frac{1}{\sqrt{2}}\bigl(\left|H_{A},H_{B}\right\rangle + \left| V_{A},V_{B}\right\rangle\bigr)
\end{equation}
1. What is the state if the photon A passes through a...
Ok, here is the scenario, kinda weird but please entertain me. Say I had a huge amount of microwave radiation being shot in a particular direction. Let's say they have a wavelength of 1mm. How would i go about polarizing the microwave radiation?
In electrostatics, for what I understand the when I have an electric field, the density of the energy stored in it is given by the following formula:
$$W = \frac{1 }{2} E \cdot D$$But when there is some material permantent polarization the above formula fails to work.
Is this correct?
How can...
I Dont understand how light polarized along a certain axis in a prepared state can then pass through a second polarizer that is at an angle to the first. The experiment I’m trying to understand starts with unpolarized light which then passes through a first filter which vertically polarizes the...
Suppose you prepare two polarization-entangled horizontally polarized photons.
Scenario 1:
After the first photon passes through a linear polarizer oriented at 45 degrees, it will have later a 50% probability of being measured as horizontally polarized and 50% as vertically polarized. The...
Homework Statement
Starting with the second order polarization in the time domain:
(1)
I am trying derive the frequency domain form:
(2)
Multiple sources give essentially the same formula with the same integral, I have obtained the particular ones in here from those lecture notes.
My...
When 2 identical photons are incident at the same time at the input channels of a 50:50 beam splitter, quantum interference causes the elimination of the both reflected and both transmitted outcomes ##\hat{a}_{1H}^{\dagger}\hat{a}_{2H}^{\dagger}|0\rangle_1|0\rangle_2 \ne...
As is known, when calculating localized states in a crystal
it is roughly considered that the point charge is “immersed” on medium with
static dielectric constant ε.
However, a simple estimate, for example, shows that an impurity atom
with charge modulo equal to the electron charge creates at...
Suppose you have a pair of electrons in the same quantum state, and are thus spin entangled, and they absorb a pair of photons and release them at the same time. How would this affect the photons? Would the photons be entangled? Would it affect the photon spin, and if so, how would it affect the...
Homework Statement
Hi everyone,
I'm a high school teacher and every time I teach the concept of polarization, students ask me the same question and I can't answer it.
I show students this picture. The red lines show the electric field vibrations. After passing through polarizer 1, the...
Elliptically polarized light strikes a glass surface (in air) with refraction index n at Brewster's angle.
What is the polarization of the reflected ray?
How does it change if now the glass surface is partially submerged in water?
And if the glass surface is fully submerged in water?
How...
I'm working through Lahiri & Pal's book A First Book of Quantum Field Theory, Second Edition and I'm stuck on their explanation of the polarization vector in quantum electrodynamics in Chapters 8 and 9. In section 8.8, they derive a formula for the sum over the transverse polarization modes of...
Homework Statement
Suppose light is prepared in a coherent superposition of linear horizontal polarization and linear vertical polarization. What is the resulting polarization according to Jones calculus if it passes through:
a linear polarizer at a 45-degree angle (0 degrees would be...
Homework Statement
When unpolarized light passes through a polarizer, what happens?
A.The light emerges polarized in the polarizer axis direction with about 12the intensity of the incident beam.
B.The light emerges polarized perpendicular to the polarizer axis direction with about 12the...
What is the phase difference between the right circularly polarized and left circularly polarized light of the same amplitude? And how do you calculate it?