Chromatic Dispersion Values Research Articles

Impact of chromatic dispersion on the system limitation due to polarization mode dispersion

The impact of chromatic dispersion on the system limitation due to polarization mode dispersion (PMD) is investigated through Monte Carlo simulations. The waveplate model is used to realistically simulate the variation of PMD with frequency. It is shown that the effects of higher order PMD are compounded in the presence of chromatic dispersion. This can lead to a reduction in the PMD limit for large values of chromatic dispersion. However, it does not lead to a reduction in the PMD limit for the moderate levels of chromatic dispersion that would be encountered in most systems.

Wide wavelength band (1535–1560 nm and 1574–1600nm), 28 × 10 Gbit/s WDM transmission over 320 km dispersion-shifted fibre

Wide wavelength-band (1535-1560 nm and 1574-1600 nm) 28/spl times/10 Gbit/s WDM transmission over a 320 km dispersion-shifted fibre, using both conventional and gain-shifted EDFAs, is successfully demonstrated. This is achieved by employing two techniques to suppress the various nonlinear effects that depend on chromatic dispersion values: unequal channel spacing for 1550 nm band signals and dispersion pre-compensation for the 1550 and 1580 nm bands.

Performance evaluation of very long span direct detection intensity and polarization modulated systems

In this paper long distances very high capacity NRZ optical transmission systems adopting direct detection are considered in links with a low average chromatic dispersion. Particular attention is devoted to polarization modulated (PM-DD) systems. Polarization modulated systems results to he more degraded with respect to intensity modulated (IM-DD) systems by the light depolarization induced by the interplay among the Kerr effect, the ASE noise of the optical amplifiers and the polarization mode dispersion. The light depolarization is particularly strong in conditions of large spectral broadening that are met when the chromatic dispersion value is maintained very low along the link. On the other hand the use of a fluctuating chromatic dispersion with a mean value equal to zero, whereas the local dispersion is different from zero, shows the double advantage to reduce the chromatic dispersion impairments and to limit the spectral broadening. The advantages offered by this dispersion management technique have been already shown in several experiments for IM-DD systems: in this work we show that this technique is very important also for PM-DD systems since the limitation in the spectral broadening reduces the light depolarization. We show that adopting a suitable dispersion management and an opportune preamplifier optical filter transmissions at 5 Gb/s can be attained in transoceanic links by means of FM-DD systems.

Polarisation-multilevel soliton transmission

A polarisation-multilevel scheme for improving the capacity and link length of soliton transmission systems is proposed. The soliton property of compensating for detrimental effects arising from large values of chromatic dispersion and polarisation mode dispersion, renders the method particularly suitable for upgrading transmission systems based on already installed standard dispersion fibres.

Numerical simulations for power margins in soliton transmission systems over transoceanic distances

Acceptable values for filter bandwidth and amplifier output power are determined by means of numerical simulations under the criteria of tolerable maximum standard deviation of timing jitters and minimum Q factor for fixed and sliding-frequency in-line filters. The results, for chromatic dispersion values usually encountered in published experiments, represented by isojitters and iso-Q factors clearly show the existence of an optimum design area. From these diagrams, the optimum bandwidth can be obtained for the largest power margin. We also analyze power margins with increasing sliding rates of in-line filters. In our simulations we obtain a 1.5-dB power margin with fixed filters and a 3-dB power margin with sliding filters.

Evaluation of chromatic dispersion in erbium doped fibre amplifiers

The value of chromatic dispersion D throughout the gain spectrum of erbium doped fibre amplifiers (EDFA) is derived from the experimental measurement of the erbium ion susceptibility. The expression of D has been redefined (D*) in units of ps/nm/dB to give a practical value of this quantity. The results provided by the derivation show that chromatic dispersion is more relevant and reaches its maximum values D* = ± 7 fs/nm/dB around the 1532 nm gain peak of EDFA.

Chromatic dispersion measurement over a 120 km dispersion-shifted single-mode fibre in the 1.5 μm wavelength region

Chromatic dispersion in the 1.47-1.60 μm wavelength region is measured successfully for a dispersion-shifted fibre over 120 km by the LD phase-shift method. The measured value of a 123 km spliced fibre agrees well with the sum of chromatic dispersion values of its constituent fibres. This confirms the additive rule of chromatic dispersion for long dispersion shifted fibre in the 1.5 μm wavelength region.