Naomi Kumano, Kazunori Mukasa, Misao Sakano and Hideya Moridaira
As a next-generation medium for overland fiber-optic transmission links that offers a wider range of signal wavelengths and Raman amplification, a new type of non-zero dispersion shifted fiber (NZ-DSF) has been developed, which has a dispersion slope only about one half that of conventional NZ-DSFs with low dispersion slope.
Generally speaking a lowering of the dispersion slope is accompanied by a contraction in the effective area of the core (Aeff), but what is needed, on the contrary, is an expansion of Aeff to overcome non-linear phenomena that hamper WDM transmission. In the work reported here it has been possible, by optimizing the refractive index profile, to lower the dispersion slope to only 0.020 ps/nm2/km, while maintaining Aeff at 45µm2--about the same as for conventional DSFs. Lowering the dispersion slope also resulted in a shift of the zero-dispersion wavelength to the shorter side, thereby not only expanding the transmission range but also enabling suppression of four wave mixing (FWM) in the pumping wavelength region when Raman amplification is applied.
It has been confirmed by a transmission simulator of the performance of the prototype NZ-DSF that 10 Gbps transmission can be achieved, and the application of a dispersion compensator for even higher rates is under consideration.