Deterministic nature of polarisation mode dispersion in fibre amplifiers

PMD measurements on installed fibers and polarization sensitive components

“…14. As it is apparent, the PMD is very small and deterministic, since at each wavelength the DGD variance is much smaller than the mean value. In contrast with the previous two cases, the active fiber is only 5 m long and it resembles the case of C-EDFA [12]. These results demonstrate that, although the active medium is very long, PMD of L-EDFAs can be effectively controlled in the packaged OFA device.…”

“…LEDFAs for optical amplification in the L-band (1570-1615 nm) are made by very long active fibers (up to 200 m and more), in order to transfer to longer signal wavelengths the pump energy as well as the energy of Amplified Spontaneous Emission (ASE) generated in the C-band (1530-1565 nm). It has already been shown that PMD in C-EDFAs and Erbium-Doped Fluoride Fiber Amplifiers (EDFFAs) is very small as well as deterministic [12]. This means that, even in a long-haul, high-bit-rate optically amplified link, the OFA contribution to the total PMD is small (order of 0.05-0.3 ps deterministic Differential Group Delay DGD per amplifier [13]) and can be characterized by a well defined DGD maximum value over the gain bandwidth.…”

“…In the PMD measurements presented below, the input and output components were tested separately from the active fibers, in order to discriminate between the expected deterministic and possible stochastic contributions to the OFA PMD. The measurements were performed by means of the JME technique because, due to its high immunity to the OFA ASE noise (the JME uses only the polarized part of the optical signal), it is the most appropriate method for measurements on working optical amplifiers [12]. The input and output coupling components were characterized by placing a polarization scrambler in between them, to evaluate their total PMD under different (stochastic) coupling, simulating the possible behavior of the active fiber.…”