# Light Polarization and Stokes Parameters

Light Polarization and Stokes Parameters

The polarization state of an electromagnetic wave can conveniently be described by a set of Stokes parameters. On the left, the polarization ellipse describes the motion of the optical electric field (,) in a plane transverse to the light propagation direction. On the right are the corresponding Stokes parameters defined in terms of intensity difference measurements

E

H

E

V

iΔϕ

e

S

x

I

H

I

V

2

E

H

2

E

V

S

y

I

-45°

I

+45°

E

H

E

V

S

z

I

L

I

R

E

H

E

V

where the intensities of the polarization components (: horizontal, : vertical, ±45: along diagonals, : circular left, : circular right) are normalized to the total light intensity. The parameters that you can vary are the orientation of the ellipse, its degree of linear polarization , where and are the intensities measured along the major and minor axes, and its handedness (direction of rotation). For 100% polarized light, the endpoint of the Stokes vector =(,,) lies on a unit sphere called the Poincaré sphere.

H

V

°

L

R

DOLP=-+

I

max

I

min

I

max

I

min

I

max

I

min

S

S

x

S

y

S

z