The Luna Quarterly

The Importance of Measuring Polarization Extinction Ratio (PER)

Measuring PER in optical fiber

When dealing with highly birefringent optical components, such as polarization maintaining (PM) fibers and integrated waveguides, the ability to maintain a stable and linear state of polarization (SOP) is essential for the successful operation of many high-speed optical modulators, fiber sensors, optical imaging systems and fiber optic gyroscopes (FOGs).

In practice, however, due to fiber orientation misalignment, connectors misalignment, bad splices, temperature and stress variations, as well as fiber and waveguide imperfections, some light on the principal polarization mode couples onto the orthogonal one (also known as polarization cross-talk), changing the SOP at the output. The ratio between the total optical power of the signal on the SOP on which it is supposed to propagate and the total optical power on the orthogonal is referred to as the polarization extinction ratio (PER). 

Accurately measuring the total PER of PM fibers and waveguides, well as identifying the locations of high polarization cross-talks along an optical path is critical. Luna Innovations has multiple solutions and different measurement techniques to measure not only the total PER but also the distributed polarization cross-talks with high accuracy and repeatability.

Learn more by watching the recent on-demand webinar on measuring PER here.