Yuji Kodama

Chirped nonlinear pulse propagation in a dispersion-compensated system

We study nonlinear pulse propagation in an optical transmission system with dispersion compensation. A chirped nonlinear pulse can propagate in such a system, but eventually it decays into dispersive waves in a way similar to the tunneling effect in quantum mechanics. The pulse consists of a quadratic potential that is due to chirp in addition to the usual self-trapping potential and is responsible for the power enhancement and the decay.

Interactions between dispersion managed solitons in optical-time-division-multiplexed system

Nonlinear interactions between neighboring pulses in optical-time-division-multiplexed (OTDM) systems may cause a timing jitter of the signal pulse, which results in a limitation of the transmission distance and bit-rate. We show that alternating the phases or amplitudes of pulses in the time sequence is effective for reducing the interactions between dispersion managed solitons as in the case of ideal solitons, but only for a relatively weak dispersion management.

Reduction of Gordon-Haus jitter in a dispersion compensated optical transmission system: analysis

Abstract We theoretically analyze the Gordon-Haus timing jitter in an optical transmission system with dispersion compensation. The enhanced power obtained in such a system reduces the frequency shift induced by noise, and choosing an appropriate position of the receiver further reduces the timing jitter converted from the frequency shift. Based on these results, we can obtain the reduction of the Gordon-Haus timing jitter in a dispersion compensated system, compared with a conventional soliton having equal pulse width and path-average dispersion.

Optimal allocation of amplifiers in a dispersion-managed line for a wavelength-division-multiplexed soliton transmission system

Optimal allocation of amplifiers in a dispersion-managed line is theoretically derived by means of minimizing the collision-induced frequency shift in a two-channel wavelength-division-multiplexed soliton transmission system. Almost complete cancellation of the frequency shift can be obtained for such a system with any strength of dispersion management.

Analysis of Gordon-Haus jitter in a dispersion-compensated optical transmission system.

We theoretically analyzed the Gordon-Haus timing jitter in a periodically dispersion-compensated optical transmission system as a result of upgrading a preinstalled uniform-dispersion system. We show that the enhanced peak power for a large dispersion difference in the period reduces the frequency shift induced by noise, and a proper setting of the receiver position further reduces the timing jitter.

Optimal design of dispersion management for a soliton–wavelength-division-multiplexed system

We obtain analytical formulas for minimizing chirp and timing jitter that lead to optimal designs for a soliton-wavelength-division-multiplexed system with dispersion management and lumped amplifiers. The method used here is the guiding-center theory, from which we obtain a stationary pulse shape (guiding-center soliton) that has enhanced power and an increased time-bandwidth product compared with those of a soliton alone.

Adiabatic soliton transmission in fibers with lumped amplifiers: analysis

By proper dispersion management an ideal adiabatic transmission of optical solitons is possible in fibers with loss compensated by periodic lumped amplifiers. For a practical design with stepwise dispersion, nonsoliton (radiation) components are estimated by the perturbed inverse-scattering method. Finally, radiation that is due to soliton–soliton collision in a wavelength-division-multiplexed system is also analyzed.

Effects of filters on pulse-to-pulse interaction between dispersion-managed solitons

Interaction between adjacent soliton-like pulses in periodic dispersion-managed transmission systems with lumped amplifiers and filters is analyzed. It is shown that the averaged motion of interacting pulses may become slightly repulsive in the initial stage of propagation depending on the amplifier location in a unit cell of the dispersion management. It is further shown that for the case of initial pulse repulsion, the guiding filters have significant effect on increasing the collapse distance of the pulses.

Input pulse optimization in wavelength-division-multiplexed soliton transmissions

Abstract Amplitudes of input pulses in different channels of wavelength-division-multiplexed soliton transmissions should be adjusted according to their wavelength shift. The optimal distribution of input amplitudes maintains the initial time width and minimizes the radiations. Numerical simulations indicate that using this simple method, WDM transmission capacities of 80 Gbit/s over transoceanic distances may be possible in dispersion-managed fiber links without introducing any in-line soliton controls.

Analysis of Gordon-Haus Jitter in Dispersion Compensated Optical Fibers

We theoretically analyze the Gordon-Haus timing jitter in an optical transmission system with a dispersion compensation. The enhanced power obtained in the system reduces the frequency shift induced by the noise, and a choice of an appropriate position of the receiver further reduces the timing jitter. Based on these results, we obtain the reduction of the Gordon-Haus timing jitter for the pulse in the dispersion compensated system. The reduction is more when compared with a soliton having equal pulse width and path-averaged dispersion.