# Documentation

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# stokes

Stokes parameters of polarized field

G = stokes(fv)
stokes(fv)

## Description

example

G = stokes(fv) returns the four Stokes parameters G of a polarized field or set of fields specified in fv. The field should be expressed in terms of linear polarization components. The expression of a field in terms of a two-row vector of linear polarization components is called the Jones vector formalism.

example

stokes(fv) displays the Stokes parameters corresponding to fv as points on the Poincare sphere.

## Examples

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Create a left circularly-polarized field. Convert it to a linear representation and compute the Stokes vector.

cfv = [2;0];
fv = circpol2pol(cfv);
G = stokes(fv)
G =

4.0000
0
0
4.0000

Display points on the Poincare sphere for a left circularly-polarized field and a 45° linear polarized field.

fv = [sqrt(2)/2, 1; sqrt(2)/2*1i, 1];
G = stokes(fv)
G =

1.0000    2.0000
0         0
0    2.0000
1.0000         0

stokes(fv);

The point at the north pole represents the left circularly-polarized field. The point on the equator represents the 45° linear polarized field.

## Input Arguments

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Field vector in its linear polarization representation specified as a 2-by-N complex-valued matrix or in its linear polarization ratio representation specified as a 1-by-N complex-valued row vector. If fv is a matrix, each column of fv represents a field in the form [Eh;Ev], where Eh and Ev are its horizontal and vertical linear polarization components. The expression of a field in terms of a two-row vector of linear polarization components is called the Jones vector formalism. If fv is a vector, each entry in fv is contains the polarization ratio, Ev/Eh.

Example: [sqrt(2)/2*1i; 1]

Data Types: double
Complex Number Support: Yes

## Output Arguments

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G contains the four Stokes parameters for each polarized field specified in fv. The Stokes parameters are computed from combinations of intensities of the field:

• G0 describes the total intensity of the field.

• G1 describes the preponderance of horizontal linear polarization intensity over vertical linear polarization intensity.

• G2 describes the preponderance of +45° linear polarization intensity over -45° linear polarization intensity.

• G3 describes the preponderance of right circular polarization intensity over left circular polarization intensity.

## References

[1] Mott, H., Antennas for Radar and Communications, John Wiley & Sons, 1992.

[2] Jackson, J.D. , Classical Electrodynamics, 3rd Edition, John Wiley & Sons, 1998, pp. 299–302.

[3] Born, M. and E. Wolf, Principles of Optics, 7th Edition, Cambridge: Cambridge University Press, 1999, pp 25–32.