Numerical analysis of athermal DPSK based on unbalanced thermally expanded core optical fibers Mach Zehnder interferometer

Simulations are performed to determine the fundamental mode effective index thermal dependence of a thermally expanded core single mode optical fiber. We point out that the thermal dépendance of the fundamental mode effective index (dneff/dT) of a thermally diffused optical fiber decrease when the mode field diameter increase. A passively temperature independent fibre-type optical DPSK based on Mach-Zehnder interferometer design is proposed by using thermally expanded core optical fibre in one arm. Numerical computations of the eye diagram amplitude degradation are reported for both compensated and uncompensated DPSK designs.