Metrological Traceability of High Polarization Extinction Ratio (PER) Based on Precision Coaxial Rotating Polarization-Maintaining Fiber

This article proposes a metrological traceability method for polarization extinction ratio (PER) ranging from 0 up to 70 dB, while the common method is limited to 50 dB. A precision alignment coupling point is designed and manufactured using two polarization-maintaining fibers (PMFs). By rotating one of the PMFs to change the axis-alignment angle and to control the distribution of light energy in the fast and slow axis, a traceability chain from the PER to the rotation angle is established. With extremely low-stress clamping of the PMF, 5-D precision adjustment of the fiber position, and precision coaxial rotation in the order of arc seconds, accurate and controllable generation of any PER in the range of 0-70 dB can be achieved. A high PER traceability system is designed and built, which is successfully used in the traceability of PER to the angle of circumference. The expanded uncertainty ( k = 2 ) in the ranges of 0-30 dB, 30-50 dB, and 50-70 dB is 0.01, 0.06, and 1.20 dB, respectively. Controlled generation of high PER (50-70 dB) with metrological traceability is realized for the first time as far as we know.