Wiki / Polarization / Polarizer

Polarizer

Applies a linear polarization axis and Malus-law attenuation.

Open in the canvas →

Click the polarizer to see its live specs and try its parameters — this mini canvas can't be moved, deleted, or added to.

In the real world

An ideal linear polarizer transmits only the field component parallel to its transmission axis. For fully polarized light arriving at angle θ to that axis, the classic form of Malus's law gives the transmitted intensity:

I=I0cos2θI = I_0 \cos^{2}\theta
Malus's law for fully (linearly) polarized input.

That scalar formula only covers fully linearly polarized light, though — it says nothing about partially polarized, unpolarized, or elliptically polarized input, which is most real light sources.

In OpticalSetup

Polarization state throughout OpticalSetup is tracked as a full normalized Stokes vector (s₁, s₂, s₃), not a single angle — so a polarizer's transmission is computed with the general form of Malus's law, which reduces to the scalar equation above for fully linear light but also gives the correct partial transmission for unpolarized, partially polarized, or circular input:

T=12(1+s1cos2θ+s2sin2θ)T = \tfrac{1}{2}\left(1 + s_1\cos 2\theta + s_2\sin 2\theta\right)
The Stokes-vector form of Malus's law that OpticalSetup evaluates at every polarizer.
Simplified vs. reality

The polarizer is ideal — perfect extinction on the blocked axis, no wavelength dependence, no insertion loss on the transmission axis.

Related components

Further reading