The POS-002 polarization tracker automatically adjusts the state of polarization (SOP) towards a reference SOP, counteracting continuous input SOP variations as fast as 0.9 ms with no resets. The reference SOP is determined by a feedback signal which can be provided either internally or externally. The internal feedback version (POS-002-I) consists of a fiber squeezer polarization controller, in-line polarization monitor, digital and analog circuits, and proprietary algorithm. The error signal from the polarization monitor is fed back to the polarization controller to maintain a linear SOP at the output. The output fiber is typically PM fiber with the SOP aligned to its slow axis.

The external feedback version (POS-002-E) replaces the internal polarization monitor with an external analog electrical feedback signal of the user’s choice, such as a voltage proportional to the degree of polarization (DOP) measured by a polarimeter, the bit-error rate (BER) from a BER chip, the RF spectrum of a detected signal, or the optical power after a polarizer. The output fiber is typically single mode fiber.