Traceable Measurement of High Polarization Extinction Ratio Based on Machine Vision

Based on the principle of white-light interference, the polarization-maintaining fiber (PMF) coaxial alignment device can realize the continuous and controllable generation of the polarization extinction ratio (PER) value by establishing the quantitative traceability relationship between PER value and PMF coaxial rotating angle <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\theta $ </tex-math></inline-formula>. The single-point PMF coaxial alignment rotation can generate a PER value of 0 dB ~ 80 dB. The PER value generated by the two-point superposition method can be doubled in theory. Arbitrary PER value calibration in the range of 0 dB ~ 100 dB is implemented by basing on machine vision to assist in aligning PMF to reduce the influence of the coupling point position error. The experimental result shows that the PMF coaxial alignment device with two-point superposition can generate any PER value from 0 dB ~ 100 dB through the auxiliary alignment by the Extremal Variances Sum Method of linear detection.