Four-Channel All-Fiber Dispersion-Managed 2R Regenerator

Abstract

Abstract-We experimentally investigate a dispersion-managed four-channel 2R regenerator that relies on self-phase modulationinduced spectral broadening and offset filtering at four shifted wavelengths. The device consists of several alternating sections of dispersion-compensating fibers and single-mode fibers. Due to this arrangement and the use of low duty-cycle return-to-zero pulses, nonlinear interchannel effects are sufficiently mitigated resulting in almost no additional degradation compared to the single-channel case.

Progress in Multichannel All-Optical Regeneration Based on Fiber Technology

“…In a second approach, inter-channel crosstalk is avoided by time interleaving the input signals [28][29][30][31][32]. In these schemes, the various WDM channels are properly spaced in time before entering the regenerator, see Fig.1 (b).…”

“…In these schemes, the various WDM channels are properly spaced in time before entering the regenerator, see Fig.1 (b). This approach has been investigated in both fiber [28][29][30][31] and SOA technologies [32]. The WDM channels are then processed at once in a serial fashion in a single nonlinear medium, guaranteeing a reduction of cost as the number of channels increases.…”

“…However, the WDM channels need to be synchronous and with a relatively low duty cycle, since the maximum pulse width that a channel can occupy is determined by the number of WDM channels simultaneously processed by the regenerator. The WDM synchronicity can be achieved by either using appropriate delay lines located within a demultiplexer/multiplexer apparatus [30][31][32] or making the WDM channels properly time-aligned at the regenerator input using specific wavelength-mapping rules [28][29]. To achieve the correct duty cycle, a pulse compression stage is likely to be needed prior to the regenerator (see Fig.1 (b)), making, however, the use of the bandwidth of the transmission line relatively inefficient and the whole arrangement quite complicated as the number of WDM channels increases.…”

“…Finally, in a third approach, which has been developed for WDM OOK signals, carefully engineered dispersive walkthrough maps in fibers are used to avoid the inter-channel crosstalk [30,[33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48]. In these schemes a high local average dispersion value ensures that the nonlinear inter-channel effects are significantly weaker due to the fast walk-off time among the various WDM channels, while a low overall average dispersion value ensures that the nonlinear effect used for the regeneration process itself (SPM) is sufficiently retained, Fig.1 (c).…”

“…It is, though, worth pointing out that, to date, SPM-based regenerators are the most promising ones due to their simple implementation and excellent performance and thus the easiest to be adapted for multi-wavelength operation if OOK signals are used. These types of SPM-based regenerators differ in their architectures, according to whether the various WDM channels all propagate in the same direction [30,[33][34][35][36][37][38][39][40][41] or some in opposite directions [42][43][44][45][46][47][48] within the nonlinear fiber, see Fig. 1 (c.i-v).…”