Linear polarization

The classical sinusoidal plane wave solution of the electromagnetic wave equation for the electric and magnetic fields is (cgs units)

${\displaystyle \mathbf {E} (\mathbf {r} ,t)=|\mathbf {E} |\mathrm {Re} \left\{|\psi \rangle \exp \left[i\left(kz-\omega t\right)\right]\right\}}$ 

${\displaystyle \mathbf {B} (\mathbf {r} ,t)={\hat {\mathbf {z} }}\times \mathbf {E} (\mathbf {r} ,t)/c}$ 

for the magnetic field, where k is the wavenumber,

${\displaystyle \omega _{}^{}=ck}$ 

is the angular frequency of the wave, and ${\displaystyle c}$  is the speed of light.

Here ${\displaystyle \mid \mathbf {E} \mid }$  is the amplitude of the field and

${\displaystyle |\psi \rangle \ {\stackrel {\mathrm {def} }{=}}\ {\begin{pmatrix}\psi _{x}\\\psi _{y}\end{pmatrix}}={\begin{pmatrix}\cos \theta \exp \left(i\alpha _{x}\right)\\\sin \theta \exp \left(i\alpha _{y}\right)\end{pmatrix}}}$ 

is the Jones vector in the x-y plane.

The wave is linearly polarized when the phase angles ${\displaystyle \alpha _{x}^{},\alpha _{y}}$  are equal,

${\displaystyle \alpha _{x}=\alpha _{y}\ {\stackrel {\mathrm {def} }{=}}\ \alpha }$ .

This represents a wave polarized at an angle ${\displaystyle \theta }$  with respect to the x axis. In that case, the Jones vector can be written

${\displaystyle |\psi \rangle ={\begin{pmatrix}\cos \theta \\\sin \theta \end{pmatrix}}\exp \left(i\alpha \right)}$ .

The state vectors for linear polarization in x or y are special cases of this state vector.

If unit vectors are defined such that

${\displaystyle |x\rangle \ {\stackrel {\mathrm {def} }{=}}\ {\begin{pmatrix}1\\0\end{pmatrix}}}$ 

and

${\displaystyle |y\rangle \ {\stackrel {\mathrm {def} }{=}}\ {\begin{pmatrix}0\\1\end{pmatrix}}}$ 

then the polarization state can be written in the "x-y basis" as

${\displaystyle |\psi \rangle =\cos \theta \exp \left(i\alpha \right)|x\rangle +\sin \theta \exp \left(i\alpha \right)|y\rangle =\psi _{x}|x\rangle +\psi _{y}|y\rangle }$ .

• Sinusoidal plane-wave solutions of the electromagnetic wave equation
• Polarization
  • Circular polarization
  • Elliptical polarization
  • Plane of polarization
• Photon polarization

• Jackson, John D. (1998). Classical Electrodynamics (3rd ed.). Wiley. ISBN 0-471-30932-X.

• Animation of Linear Polarization (on YouTube)
• Comparison of Linear Polarization with Circular and Elliptical Polarizations (YouTube Animation)

  This article incorporates public domain material from Federal Standard 1037C. General Services Administration. Archived from the original on January 22, 2022.