Analytical form of frequency dependence of DGD in concatenated single-mode fiber systems

An analytical form for the lightwave angular frequency (ω) dependence of the squared value of the differential group delay in concatenated single-mode optical fiber systems is introduced. We show that the dependence can be described by a combination of cosine functions of rotation angles and their sums and differences of the fiber pieces, which are located between the two end pieces of the concatenated system. Using the analytical expression, the ω dependence of real fiber systems can be simulated, providing information about the birefringence configuration of the system. Comparison with experimental data taken on real systems yields good qualitative agreement even if only few concatenations are considered.