Design of multilevel amplitude regenerative system

Abstract

We propose a scheme for multilevel (nine or more) amplitude regeneration based on a nonlinear optical loop mirror (NOLM) and demonstrate through numerical modeling its efficiency and cascadability on circular 16-, 64-, and 256-symbol constellations. We show that the amplitude noise is efficiently suppressed. The design is flexible and enables variation of the number of levels and their positioning. The scheme is compatible with phase regenerators. Also, compared to the traditional single-NOLM configuration scheme, new features, such as reduced and sign-varied power-dependent phase shift, are available. The model is simple to implement, as it requires only two couplers in addition to the traditional NOLM, and offers a vast range of optimization parameters.

Regeneration limit of classical Shannon capacity

“…30, it is challenging to regenerate high-order constellations (higher than 32) using the conventional approach of regenerating phase and amplitude, as such constellations have tight phase packing due to energy efficiency requirements. Therefore, a new approach for regenerating separately the two signal quadratures will be required.…”

Advanced 3R regenerator scheme for high spectral efficient signal waveforms

“…However, with the recent introduction of highly spectral efficient signals, characterized by non-return to zero (NRZ) modulation of complex constellations, the re-timing functionality was overlooked. The efforts mostly were focused in advancing the 2R performance through schemes that could remove the noise from the multiple amplitude and phase levels of the signal waveform [1]- [3]. However, in future transmission links the channels will be densely packed and tight filtering will be required for any in-line channel selection, e.g.…”

Information theory analysis of regenerative channels

“…The latter scenario can be realized by means of all-optical regenerators. Recent progress in the field has led to a variety of such subsystems, characterized by different transfer functions [2]- [4], that accordingly define nonlinear channels of different properties. As there is a surge in search of new techniques to increase the information throughput, all-optical regeneration represents a unique solution for improving the transparent length and enabling high capacity networking.…”