POLARIZATION-DEPENDENT COUPLING IN TWIN-CORE FIBERS WITH ARBITRARY ELLIPTIC CORES

Polarisation-dependent coupling in a twin-elliptical-core optical fibr e, whose cores possess both an arbitrary core eccentricity and orienta tion, is investigated. Exact numerical results are presented that dete rmine the degree of form birefringence and permit the accuracy of stan dard approximation techniques to be evaluated. A comparison of the the oretical x-and y-polarisation coupling coefficients with experimental data suggests that stress-induced birefringence is dominant in practic e.