This video demonstrates an easy, fast, and accurate way to measure the polarization extinction ratio (PER) of a bare polarization maintaining (PM) fiber. It is defined as the ratio of the power in the principal polarization mode to the power in the orthogonal polarization mode after propagation through a device or. Extinction ratio tester,Ideal PhotonicsSpecializing in global instrument distribution and system integration for MCT detectors, semiconductor laser diodes, mid-infrared QCL lasers, fiber amplifiers, photodetectors, HeCd lasers, gas lasers, narrow-linewidth lasers, OCT system fiber fusion tapering. Polarization Extinction Ratio Meter & Polarized Sources • LOW COST!.