Toshihiko Hirooka

Resonant nonlinear intrachannel interactions in strongly dispersion-managed transmission systems

Nonlinear intrachannel interactions in a transmission system with strong periodic dispersion management are studied. The ghost pulse at the zero bit is shown to grow resonantly as a result of periodic forcing and temporal phase matching with the signal pulses. The growth rate depends on the degree of overlap between the signals. The analysis agrees with direct numerical simulation of the full system. Growth rates for various bit patterns as a function of map strength are obtained.

Quasi-linear optical pulses in strongly dispersion-managed transmission systems

A unified analytical description of the evolution of quasi-linear optical pulses and solitons in strongly dispersion-managed transmission systems is developed. Asymptotic analysis of the nonlocal equation that describes the averaged dynamics of a dispersion-managed system shows that the nonlinearity decreases for large map strength s , as O(log s/s) . The spectral intensity is found to be an invariant of the propagation, which allows the phase shift to be computed. These findings provide a clear description of pulse propagation in the quasi-linear regime, which is characterized by much lower energies than those required for stable dispersion-managed soliton transmission with the same dispersion map.

Resonant intrachannel pulse interactions in dispersion-managed transmission systems

Nonlinear intrachannel interactions in a transmission system with strong periodic dispersion management are investigated. An analytical model that describes the fluctuation of the temporal position and amplitude of the main signal and ghost pulse generation at zero bits due to intrachannel crosstalk is developed. Intrachannel nonlinear effects are found to be a resonant process which is induced by periodic forcing due to lumped amplification assisted by temporal phase matching. Explicit formulae to estimate transmission impairments such as timing and amplitude jitter are provided based on the analytical model. The role of distributed amplification to suppress intrachannel nonlinear effects is also discussed. A more fundamental analytical framework which enables one to evaluate intrachannel crosstalk over a wide regime of system configurations is also presented.

Managing nonlinearity in strongly dispersion-managed optical pulse transmission

An analytical description of the propagation of quasi-linear optical pulses in strongly dispersion-managed systems is presented. The effect of nonlinearity on quasi-linear pulse transmission is studied by asymptotic analysis of a nonlocal equation that describes the average dynamics of a dispersion-managed system. The spectral intensity is found to be an invariant of propagation in a lossless model even in the presence of nonlinearity, whereas in a system with loss and periodic amplification the spectral characteristics of evolution depend on the relative position of the amplifier in the dispersion map. The analytical results obtained here agree with direct numerical simulations and recent experimental observations.

Higher-order asymptotic analysis of dispersion-managed transmission systems: solutions and their characteristics

A higher-order, multiple-scale asymptotic analysis is made of the perturbed nonlinear Schrodinger equation in a strong dispersion-managed optical transmission system. It is found that the averaged equation with the next-order term included significantly improves the description of the characteristics of dispersion-managed solitons. The derived equation is shown to support a new class of soliton solutions, namely, multihump solitons, which depend on both the map strength and dispersion profile. Numerical evidence of the regions of existence and stability of such new solitons is discussed.

Intrachannel pulse interactions in dispersion-managed transmission systems: energy transfer

Energy transfer between adjacent pulses as a result of nonlinear intrachannel interactions in a transmission system with strong periodic dispersion management is analyzed. With small average dispersion, the energy change between nonzero bits grows linearly with respect to distance in the presence of loss and lumped amplification, whereas in a lossless system the energy change is found to be significantly suppressed. The analytical results compare favorably with the results of direct numerical simulation of the full system.

Collision-induced timing shifts in dispersion-managed soliton systems

The frequency and timing shifts associated with dispersion-managed solitons in a wavelength-division multiplexed system are computed by the numerically efficient Poisson sum technique. Analytical formulas are attainable by use of this approach with a Gaussian approximation for the soliton. The results are favorably compared with known results for the frequency shift. The method also applies to quasi-linear return-to-zero transmission formats.

Intrachannel pulse interactions in dispersion-managed transmission systems: timing shifts.

Nonlinear intrachannel interactions responsible for timing shifts in a transmission system with strong periodic dispersion management are investigated. Formulas describing the evolution of the timing shift are obtained for general bit patterns. When average dispersion is negligible, the timing shift is shown to grow linearly in distance in a system with loss and lumped amplification, whereas in a lossless system the timing shift is sufficiently small at every chirp-free point. The analysis agrees with direct numerical simulations.

Incomplete collisions in strongly dispersion-managed return-to-zero communication systems

Incomplete collisions in wavelength-division-multiplexed return-to-zero transmission systems are analyzed by asymptotic methods. Formulas for frequency and timing shifts are obtained. The results agree with direct numerical calculations.

Analysis of timing and amplitude jitter due to intrachannel dispersion-managed pulse interactions

Transmission impairments due to nonlinear intrachannel crosstalk in strongly dispersion-managed systems are investigated. Analytical expressions to estimate timing and amplitude jitter due to intrachannel pulse interactions are provided. Timing jitter is found to be a dominant limiting factor for small values of map strength, whereas amplitude jitter is responsible for system performance degradation especially for large map strength. The analysis agrees with direct numerical simulations of the full system.