The authors examine the formation of stable soliton-like pulses in optical fibres with a periodic dispersion map. It is found that increased energy is required to launch a pulse of given width compared to the equivalent uniform fibre with equal path-average dispersion. The stable pulse shapes in dispersion managed systems are significantly different to the hyperbolic secant solitons found in uniform fibres.

Enhanced power solitons in optical fibres with periodic dispersion management

A universal post-compensation scheme for fiber impairments in wavelength-division multiplexing (WDM) systems is proposed based on coherent detection and digital signal processing (DSP). Transmission of 10 x 10 Gbit/s binary-phase-shift-keying (BPSK) signals at a channel spacing of 20 GHz over 800 km dispersion shifted fiber (DSF) has been demonstrated numerically.

Electronic post-compensation of WDM transmission impairments using coherent detection and digital signal processing.

The trend toward higher bit rates in lightwave communications has increased interest in dispersion-shifted fiber to minimize dispersion penalties. At the same time optical amplifiers have increased interest in wavelength multiplexing. These two methods of increasing system capacity, if used together, can result in severe degradation due to fiber nonlinearity. This paper discusses the impact of the principal nonlinearity, four-photon mixing, and describes strategies that allow simultaneous use of high bit rates and WDM. >

Four-photon mixing and high-speed WDM systems

An experimentally realizable scheme of periodic sign-changing modulation of the scattering length is proposed for Bose-Einstein condensates similar to dispersion-management schemes in fiber optics. Because of controlling the scattering length via the Feshbach resonance, the scheme is named Feshbach-resonance management. The modulational-instability analysis of the quasiuniform condensate driven by this scheme leads to an analog of the Kronig-Penney model. The ensuing stable localized structures are found. These include breathers, which oscillate between the Thomas-Fermi and Gaussian configuration, or may be similar to the 2-soliton state of the nonlinear Schrodinger equation, and a nearly static state ("odd soliton") with a nested dark soliton. An overall phase diagram for breathers is constructed, and full stability of the odd solitons is numerically established.

Feshbach resonance management for Bose-Einstein condensates.

The nonlinear effects in optical fiber occur either due to intensity dependence of refractive index of the medium or due to inelastic-scattering phenomenon. This paper describes various types of nonlinear effects based on first effect such as self-phase modulation, cross-phase modulation and four-wave mixing. Their thresholds, managements and applications are also discussed; and comparative study of these effects is presented.

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Nonlinear Effects in Optical Fibers: Origin, Management and Applications

A specific fiber dispersion management is proposed allowing the simultaneous suppression of linear dispersion penalties and of degradations arising from parametrical fiber nonlinearities. For the proposed dual dispersion configuration (DDCON) the number of optical channels that can be transmitted over 1000 km at a bit rate of 2.5 Gb/s is only limited by the available optical amplifier bandwidth. >

C. Kurtzke

Papers

Suppression of fiber nonlinearities by appropriate dispersion management