# Can unpolarized light be created from polarized light?

I have a question regarding this topic. According Stokes Parameters theory, unpolarized light could be described as a superposition of two independent beams of equal intensity and orthogonal polarization. For instance, using Stokes vectors:

(LHP + LVP)

$I_0\begin{pmatrix} 1 \\ 0 \\ 0 \\ 0 \end{pmatrix} = \frac{I_0}{2}\begin{pmatrix} 1 \\ 1 \\ 0 \\ 0 \end{pmatrix} + \frac{I_0}{2}\begin{pmatrix} 1 \\ -1 \\ 0 \\ 0 \end{pmatrix}$

(RCP + LCP)

$I_0\begin{pmatrix} 1 \\ 0 \\ 0 \\ 0 \end{pmatrix} = \frac{I_0}{2}\begin{pmatrix} 1 \\ 0 \\ 0 \\ 1 \end{pmatrix} + \frac{I_0}{2}\begin{pmatrix} 1 \\ 0 \\ 0 \\ -1 \end{pmatrix}$

My question is: can I generate unpolarized light in a lab by combining two different light beams which fulfill the previous requirements?

• Are you missing a factor of 1/2? – G. Paily Nov 26 '14 at 0:56

Adding two stokes vectors does not give you the stokes vector for the combination of the two beams. For example, adding a beam of horizontal and vertical polarization would make a beam of 45deg (linear) polarization. In order to add two beams you would have to come up with a Muller matrix $M_\vec{a}$ for adding $\vec{x}$ to $\vec{a}$.