Comment on ´Polarisation mode dispersion measurements in 1520 km EDFA system´

For the original article see ibid., vol.28, no.9, p.881-3 (1992). The commenter states that in the above mentioned paper by Y. Namihira et al. two different results are reported on differential group delay (DGD) Delta tau in a link consisting of 23 fibres and 22 erbium-doped fibre amplifiers (EDFAs): an estimated value of 7.6 ps and an experimental value of 5 ps. He then points out that the authors did not clarify how the estimated result was obtained and in his opinion therefore the estimated value cannot be considered to be ´in good agreement´ with the experimental result. The commenter goes on to derive a model which he considers to be more correct, giving a closer agreement between the values.