The POS-202, POS-203 and POS-204 polarization stabilizers maintain stable output states of polarization (SOP) against rapid input SOP fluctuations, compensating for an input polarization discontinuity in as fast as 5 ms, or tracking without resets against a continuous input SOP rotation of up to 32π/s. The POS-20X architecture includes a polarization controller, in-line polarization monitor, and proprietary algorithms.

The POS-203 has optical ports for signal input and output and a third port for an optical feedback signal. It automatically optimizes the output SOP to either maximize or minimize and optical or electrical feedback signal. It also allows the operator to control the step size, feedback delay, activation threshold, and search algorithm (maximum or minimum) from the front panel as well as remotely via one of the digital interfaces.