A method for the adaptive adjustment of a PMD compensator in optical fiber
communication systems comprises the steps of taking the signal at the
compensator output and extracting the components y.sub.1(t) and
y.sub.2(t) on the two orthogonal polarizations, computing the signal
y(t)=[y.sub.1(t)].sup.2+[y.sub.2(t)].sup.2, sampling the signal y(t) at
instants t.sub.k=kT with T=symbol interval to obtain samples y(t.sub.k),
computing the mean square error e(k)=y(t.sub.k)-u(k) with u(k) equal to
the symbol transmitted, and adjusting the parameters of the compensator
to seek to minimize e(k). A PMD compensator in accordance with the method
comprises an adjustment system which comprises in turn a photodetecor
(17) which takes the components y.sub.1(t) and y.sub.2(t) on the two
orthogonal polarizations from the signal at the compensator output, a
sampler (19) which samples at instants t.sub.k=kT with T=symbol interval,
the signal y(t)=[y.sub.1(t)].sup.2+[y.sub.2(t)].sup.2 at the output of
the photodetector (17) to obtain samples y(t.sub.k), a circuit (18, 20)
for computation of the mean square error e(k)=y(t.sub.k)-u(k) with u(k)
equal to the symbol transmitted, and a regulator (15, 16) which regulates
the parameters of the compensator to seek to minimize e(k).