Active control and detection of two nearly orthogonal polarizations in a fiber for heterodyne interferometry

摘要

A polarization control system includes a light source that generates two light beams with different polarization states and optical frequencies. A polarization state modulator changes the polarization states of the two light beams. A first detector path generates a first beat signal from the two light beams passing through a first polarizer. A second detector path generates a second beat signal from the two light beams passing through a second polarizer that is oriented substantially orthogonal to the first polarizer. An amplitude detector generates an amplitude beat signal from the first and the second beat signals. The system then uses the amplitude beat signal to determine how to adjust the polarization state modulator in order to generate the first and the second light beams with the desired polarization states.