Periodic Dispersion Compensation Research Articles

Tuning of in-line filter position for dispersion-managed soliton transmission

We optimise the positioning of guiding filters in a fiber-optic transmission system with periodic dispersion compensation. It is shown that stabilization of pulse energy fluctuations and interaction reduction for adjacent pulses that propagate in the same channel may be achieved whenever the filters are placed at optimal points within the map.

40 Gbit/s straight-line RZ data transmission over240 km of standard fibre

40 Gbit/s straight-line RZ data transmission over 240 km of standard fibre The authors report straight-line single-channel 40 Gbit/s RZ data transmission over 240 km of standard fibre with periodic dispersion compensation. To the authors' knowledge, this is the longest transmission distance reported in a straight-line transmission experiment, at 40 Gbit/s without any precoding. The back-to-back receiver sensitivity of the system was –18.9 dBm for a BER of 10-9. Transmitting data over 240 km of fibre induced a sensitivity penalty of 0.4 dB for a BER of 10-9.

Modulation instability in long amplified links with strong dispersion compensation

Modulation instability is analytically investigated in conventional fiber links exploiting periodic chromatic dispersion compensation and optical amplification. The exact solution of the propagation equation for low perturbations shows that, when linear dispersion compensators are used, the gain spectrum may be determined by just averaging the span dispersion. However if almost complete compensation is applied in each amplified span, the peak gain and frequency detuning largely deviate from this behavior. Moreover, in this case the instability does not significantly amplify the amplitude noise of the signal pump. This effect has a high potential impact on optical transmission system design.

Transmission over 362 km of 110 channels at 2.35 Gb/s from a spectrum-sliced femtosecond laser

We use temporal spectrum-slicing and optical time-division multiplexing to obtain 110 wavelength channels at 2.35 Gb/s from a single femtosecond fiber laser. We show that the output of this transmitter can be propagated over 362 km of standard single mode fiber using periodic amplification and dispersion compensation. Most transmitted channels have Q factors larger than 18.34 dB corresponding to error floors below 10/sup -16/.

Reduced-power optical solitons in fiber lines with short-scale dispersion management

We examine the properties of dispersion-managed (DM) solitons in fiber lines with dispersion-compensation period L much shorter than amplification distance Z(a) . DM solitons in systems with short-scale dispersion compensation have reduced power compared with DM solitons in previously studied regimes with L>/=Z(a) power (for the same local and average dispersion and the same pulse width). As a result, chirped DM soliton transmission with reasonably low power can be realized with shorter pulses when DM solitons in systems with large L/Z(a) ratios have energies that are too high to be used in practice.

Two extremely stable conditions of optical soliton transmission in periodic dispersion compensation lines

We investigated numerically nonlinear return-to-zero-pulse transmission through periodic dispersion compensation lines and clearly demarcate the two extremely stable transmission conditions. One case uses anomalous dispersion fibers as the transmission line and the other case uses normal dispersion fibers. Linear dispersion compensation elements are used in both cases so that the average dispersions are in the slightly anomalous region. These two conditions have opposite frequency chirp, and the normal dispersion fiber case indicates better characteristics than the anomalous dispersion fiber case.

Long-haul soliton WDM transmission with periodic dispersion compensation and dispersion slope compensation

A 20 Gb/s-based soliton wavelength division multiplexed (WDM) transmission experiments using periodic dispersion compensation and dispersion slope compensation were demonstrated. Accumulated dispersion slope was compensated with two methods. The first method was periodical individual dispersion compensation. By using this technique, 60 Gb/s (20 Gb/s/spl times/3 WDM) transmission over 8000 km was demonstrated. The second method was the use of a dispersion-flattened transmission fiber. 160 Gb/s (20 Gb/s/spl times/8 WDM) transmission over 4000 km using periodically dispersion compensated dispersion-flattened fiber was also demonstrated.

40 Gb/s single-channel soliton transmission over transoceanic distances by reducing Gordon-Haus timing jitter and soliton-soliton interaction

Forty Gb/s single-channel soliton transmission experiments using periodic dispersion compensation were conducted. The impact of the dispersion map on the transmission performance was experimentally investigated. The transmission performance was significantly varied with the dispersion map. The improvement of the transmission performance by the polarization division multiplexing, which reduced soliton-soliton interaction furthermore, was also confirmed. By using the polarization division multiplexing in the optimum dispersion map, 40 Gb/s single-channel transmission over 10200 km has been successfully demonstrated without any active inline transmission control.

High-nonlinearity fiber optical parametric amplifier with periodic dispersion compensation

Theory shows that the maximum gain and bandwidth of one-pump fiber optical parametric amplifiers made from high-nonlinearity fiber, operated with a pump wavelength /spl lambda//sub p/ far from the fiber zero-dispersion wavelength /spl lambda//sub 0/ can greatly be improved by periodic dispersion compensation. We have performed experiments and obtained good agreement with theory: for /spl lambda//sub p/=1542 and /spl lambda//sub 0/=1591 nm, we have increased the bandwidth from 7 to 28 nm, and the maximum gain from 15 to 20 dB, by splicing three pieces of standard fiber at regular intervals in a 40-m long nonlinear fiber.

40 Gbit/s single-channel soliton transmission over8600 kmusing periodic dispersion compensation

A 40 Gbit/s single-channel soliton transmission experiment using periodic dispersion compensation is described. By applying dispersion management and optimum initial phase modulation, single-channel 40 Gbit/s transmission over 8600 km has been successfully demonstrated, for the first time, without any active transmission control in the transmission line.

Average dark soliton dynamics in periodically dispersion compensated fiber transmission systems

We examine the formation and propagation of dark solitons in periodically dispersion compensated (PDC) fiber transmission systems. It is shown that dark solitons in PDC transmission systems are of nonhyperbolic tangent shape and require high background intensity to support. We also find that the amplifier spacing of PDC transmission systems for the dark soliton can be longer than that of the equivalent uniform fiber transmission system with equal path-average dispersion, in contrast to the bright soliton. Other differences and similarities of the dark and bright solitons due to periodic dispersion compensation are discussed as well.

Jitter suppression by guiding filters in combination with dispersion management

Enhancement of jitter suppression of a soliton by combination of fixed-frequency filters with periodic dispersion compensation is predicted in an analytical form by means of the Fokker-Planck equation for the soliton's random walk. The result depends on the dispersion-compensation period but not on the ratio of the dispersions. Another result is presented that can help one to understand jitter suppression by dispersion compensation without filters, which was observed in recent experiments.

Average dynamics of the optical soliton in communication lines with dispersion management: Analytical results

Applying asymptotic methods to a previously derived system of ordinary differential equations, we present an analytical description of the slow ~average! dynamics of self-similar breathing pulses propagating in fiber links with dispersion management. We derive asymptotic averaged quantities ~adiabatic invariants! that characterize the stable pulse propagation. In a particular, but practically important, case when the dispersion compensation period is much larger than the amplification distance we have found analytically the fixed points corresponding to the dispersion-managed solitons. @S1063-651X~98!51007-0#

160 Gbit/s (8 × 20 Gbit/s) soliton WDM transmissionexperiments usingdispersion flattened fibre and periodic dispersion compensation

160 Gbit/s (8/spl times/20 Gbit/s) soliton WDM signals were successfully transmitted over 4000 km with a BER of <10/sup -9/, by using periodically dispersion-compensated dispersion-flattened fibre with an average dispersion slope of 0.0005 ps/km/nm/sup 2/.

Soliton-based return-to-zero transmission over transoceanic distances by periodic dispersion compensation

The accumulation of Gordon–Haus jitter can be effectively suppressed by the use of periodic dispersion compensation and in-line optical filters. The feasibility of 20-Gbit/s soliton-based transoceanic systems has been confirmed through 1000-km loop transmission experiments and 8100-km straight-line transmission experiments that employed periodic dispersion compensation. For a 20-Gbit/s, 9000-km transmission system, a Q2 of 19 dB, a sufficient power window of 2.5 dB, and robustness to repeater output power reduction have been demonstrated, as has compatibility with the conventional supervision scheme. A dramatic increase in system capacity can be expected from soliton wavelength-division multiplexing with periodic compensation of dispersion and its slope.

Characteristics of Power Enhancement in Dispersion-Managed Soliton Systems

The range of applicable power enhancement factors in dispersion-managed soliton systems is investigated. For a dispersion compensation period equal to one amplifier span, it is found that the applicable power enhancement factors are not very sensitive to the dispersion perturbation. A power enhancement factor of about 2 is found to be almost optimal. However, the optimal power enhancement factor can be increased by using a compensation period covering several amplifier spans. In this case, the optimal power enhancement factor increases with the increasing dispersion perturbation.

10 Gbit/s RZ-signal transmission over 12960 kmin the anomalous regime with optimised in-line optical filters

An in-line filter arrangement is investigated experimentally for single-channel long-distance optical transmission in the anomalous region with periodic dispersion compensation. The optimal arrangement, along with the optimum compensation ratio and in-line amplifier output power, allows a 10 Gbit/s RZ signal to be successfully transmitted over 12960 km in a 720 km recirculating loop.

4 × 10 Gbit/s RZ-signal transmission over5040 kmin anomalous regime with optimallydispersion-compensated WDM channels

Allowable combinations of dispersion compensation period, compensation ratio, and line dispersion are investigated experimentally for WDM RZ-signal transmission in the anomalous dispersion region. One optimum combination enables 4 channel/spl times/10 Gbit/s RZ signals to be transmitted successfully over 5040 km in a recirculating loop.

Performance improvement by initial phase modulationin 20 Gbit/s soliton-based RZ transmissionwith periodic dispersion compensation

Transmission performance has been greatly improved by employing bit-synchronous phase modulation to source pulses in 20 Gbit/s soliton-based RZ transmission experiments. The tolerable window for both repeater output power and signal wavelength, for 9000 km transmission, was doubled with phase modulation.

Single-channel 40 Gbit/s, 5000 km straight-linesoliton transmission experiment using periodic dispersion compensation

The authors have demonstrated the effectiveness of periodic dispersion compensation and polarisation-division-multiplexing for timing jitter reduction in 40 Gbit/s single-channel soliton transmission, and have succeeded in 5000 km straight-line transmission experiments at 40 Gbit/s for the first time.