Influence of position deviations on the performance of 80 dB adjustable polarization extinction ratio generator

•The position deviations of polarization-maintaining fiber (PMF) may lead to the deterioration of the polarization extinction ratio (PER) by affecting the energy coupling process of the fast and the slow axes in an 80 dB adjustable PER generator.•The axial distance has no influence on PER. The influences of lateral misalignment and angle deflection are a square exponential relationship, which is negligible below 50 dB and increases drastically above it.•This paper provides a reference for the traceability of ultra-high PER and the research on optical fiber technologies in silicon-based photonic chips, optical waveguides, and semiconductor lasers.