Polarization controller

Polarization controllers can be implemented with free space optics, through a fiber pigtailed U-bench, for example.

In that case, the polarization of light is changed through the application of a controlled stress to the fiber itself.

For polarization controllers with automatic feedback, integrated optical lithium niobate (LiNbO3) devices are very suitable.

[2][3][4][5] Polarization controllers with tracking speeds of up to 100 krad/s on the Poincaré sphere are commercially available (see external link at the bottom).

[6][7] This way the whole normalized Stokes space can be stabilized for implementation of the BB84 or similar quantum cryptography protocol.