Development of a long-haul large-capacity wavelength-division multiplexed optical transmission line

摘要

In order to implement future long-haul large-capacity wavelength-division multiplexed (WDM) transmissions utilizing wide optical bandwidths, it has become indispensable to decrease the dispersion slope of the transmission line. To meet this requirement, hybrid transmission lines have been proposed that combine non-dispersion-shifted fiber (NDSF) with dispersion-compensating fiber (DCF). However, because DCFs generally have a large refractive index difference between the core (with high GeO{sub}2 concentration) and cladding, DCFs tend to exhibit higher transmission loss and higher nonlinearity compared with standard fibers. To overcome this drawback, it may be more effective to use low-loss and low-nonlinearity pure silica core fiber (PSCF) for the first section of the hybrid line. To further improve performance of this hybrid transmission line, an optimal design was explored that incorporated recently developed large effective-area (A{sub}(eff)) PSCF with newly designed DCFs, taking into consideration transmission loss, average dispersion slope, and nonlinearity. A hybrid optical line with an equivalent A{sub}(eff) of 60 μm{sup}2 based upon this optimized design typically exhibits a span loss as low as 0.205 dB/km (including splice losses), a span dispersion slope of 0.020 ps/nm{sup}2/km, and low nonlinearity, yielding a dispersion slope less than one fourth to one third that of conventional non-zero DSFs.