Reset-free adaptive polarization controller on a silicon-photonic platform for a self-coherent communication system

To give full play to the advantages of the self-coherent systems in the data center scene, the problem of the random walk of the polarization state of the delivered local oscillator must be solved. An adaptive polarization controller (APC) is an effective solution, with the characteristics of easy integration, low complexity, being reset-free, and so on. In this work, we experimentally demonstrated an endlessly APC based on a Mach-Zehnder interferometer on a silicon-photonic integrated circuit. The APC is thermally tuned with only two control electrodes. It endlessly stabilizes the arbitrary state of polarization (SOP) of the light to a state of equal power of the two orthogonal polarizations (X and Y). A polarization tracking speed of up to 800 rad/s is achieved.