Cd. Poole et Dl. Favin, POLARIZATION-MODE DISPERSION MEASUREMENTS BASED ON TRANSMISSION SPECTRA THROUGH A POLARIZER, Journal of lightwave technology, 12(6), 1994, pp. 917-929
Routine characterization of polarization-mode dispersion (PMD) in sing
le-mode fiber, both at the manufacturing stage and in installed system
s, requires an easy-to-implement measurement technique. One method tha
t is particularly simple to implement involves counting the number of
extrema (i.e., maxima and minima) per unit wavelength interval in the
transmission spectrum measured through a polarizer (analyzer) placed a
t the output of a test fiber. In this paper, we establish accurate equ
ations relating both the extrema density and mean-level crossing densi
ties in such spectra to the expected value of PMD. These equations are
used to measure several fiber samples, and are compared to measured v
alues obtained with a commercially available test set. It is shown tha
t measuring both mean-level crossings and extrema densities provides a
simple means for establishing whether a fiber is scaling as square-ro
ot L (long-length regime) or L (short-length regime). Using Monte Carl
o simulations, the accuracy of the fixed-analyzer measurements is exam
ined as a function of the width of the wavelength interval over which
measurements are made. In addition, the simulations indicate that fixe
d-analyzer measurements are quite robust with respect to the presence
of polarization-dependent loss (PDL) in the span, an important conside
ration for measurements in amplified systems.