Measurement of Polarisation-Mode Dispersion in Erbium-Doped Optical Fibers Using a Wavelength-Scanning Fixed-Analyser Method with Cycle Scanning

This paper presents a method for accurate measurement of polarisation mode dispersion (PMD) in erbiumdoped optical fibers (EDFs) using a wavelength-scanning fixed-analyser method in combination with cycle scanning. The high absorption properties of erbium in the spectral range from 1435 nm to 1575 nm limit the PMD measurement in this range; therefore, our measurements were performed in the extended wavelength range from 1580 nm to 1715 nm. The proposed method was applied to three EDFs with lengths of 10 m, 20 m and 30 m. The results show that the PMD values vary between 3 and 5 ps/√km, demonstrating consistent performance across different fiber lengths. This approach offers a reliable solution of PMD characterisation in EDFs where conventional telecom wavelength measurement techniques have spectral limitations due to absorption. The results support the feasibility of this method in optical system development and component validation, particularly in amplified systems where EDFs are commonly used.