Paolo Leoni

20 × 960-Gb/s Space-division-multiplexed 32QAM transmission over 60 km few-mode fiber

We show transmission of 20 wavelength-division-multiplexed (WDM) × 960-Gb/s space-division-multiplexed 32QAM modulated channels (spectral efficiency (SE) of 15 bits/s/Hz) over 60 km of few-mode fiber (FMF) with inline few-mode EDFA (FM-EDFA). Soft-decision FEC was implemented and used to achieve error-free transmission.

Field demonstration of mode-division multiplexing upgrade scenarios on commercial networks

We demonstrate three possible scenarios for upgrading current single-mode transmission networks with high capacity few-mode fiber technology using mode-division multiplexing (MDM). The results were obtained from measurements over a number of field-deployed single-mode fiber links with an additional experimental in-line amplified few-mode fiber link. The results confirm the viability of employing MDM using few-mode fiber technology to gradually replace legacy optical systems.

Employing Prism-Based Three-Spot Mode Couplers for High Capacity MDM/WDM Transmission

Based on a three-surface prism, a free space design of the three-spot mode coupler, supporting LP01 and LP11 modes, is introduced in this letter. We demonstrate 7.68 Tbit/s transmission of three mode division multiplexing (MDM) × 8 wavelength division multiplexing (WDM) × 320-Gb/s dual-polarization (DP)-32QAM over a 120 km differential-group-delay (DGD)-compensated few-mode fiber (FMF) by employing the proposed spot couplers.

30.7 Tb/s (96×320 Gb/s) DP-32QAM transmission over 19-cell Photonic Band Gap Fiber

We report for the first time coherently-detected, polarization-multiplexed transmission over photonic band gap fiber. By transmitting 96 × 320-Gb/s DP-32QAM modulated channels, a net data rate of 24 Tb/s was obtained.

Constellation Expansion for 100G Transmission

In this letter, we focus on coherently detected, non differentially encoded, polarisation division multiplexed 100G communication systems; through incorporating phase noise in the channel model, we assess the net coding gain achievable by various constellations that can be used in lieu of the conventional quadrature phase-shift keying (QPSK). Whereas the optical community put much effort into the optimization of the forward error correction codes for QPSK, trying to reduce the gap to the Shannon limit, we show that a potential gain of more than 2 dB is still available if different constellations are adopted.

Constellation expansion and multi-symbol detection for differentially encoded 100G systems

We propose an approach to differentially encoded 100G transmission that improves both spectral efficiency and OSNR performance over conventional DQPSK-based systems, demonstrating a practical performance beyond the theoretical limit of the conventional approach.

Constellation Expansion for Differentially Encoded 100G Transmission

Recent technological progress has enabled the implementation of powerful soft-decision forward error correction codes performing very close to the theoretical Shannon limit. However, recently we showed that, even when the most powerful binary codes are used, a significant potential gain remains unexploited in traditional, coherently detected, non differentially encoded, polarization division multiplexed 100G optical communication systems, when the modulation format is restricted to quadrature phase-shift keying. In this letter, we extend our previous work to the case of differentially encoded systems. Assuming again additive and phase white Gaussian noise, we show that an additional gain of 1-4.5 dB (depending on the amount of phase noise present) is available even when differential transmission is employed, if higher order constellations are used in place of quadrature phase-shift keying. Special care and suitable optimization criteria are required in the choice of the alternative signal constellations since, in contrast with the NDE case, the Euclidean distance is not a significant figure of merit anymore.

Impact of interleaving on SD-FEC operating in highly non-linear XPM-limited regime

We experimentally investigate the behavior of two SD codes in a 100G-PDM-DQPSK system with high-power 10G-OOK neighbors. We show that in the presence of sufficient interleaving the input-output BER relationship of both codes remains unaffected.

A Field Trial of Mode-Division Multiplexing

We present results of the first field trial ever to include a component of MDM. The demonstrated scenarios all confirm the possibility for a partial upgrade of legacy systems to few-mode technology.

Constellation expansion: Theoretical limits and practical examples

In optical communications the advent of coherent transmission techniques has been shortly followed by the breakthrough of soft decision (SD) forward error correction (FEC). The optical community put much effort into the design and implementation of powerful FEC codes. However, we show that, for the exemplary case of 100G polarization division multiplexed (PDM) systems, both with differential and non-differential transmission, a potential gain of more than 1 dB is still available if coding and modulation are jointly optimized. The benefits of this approach are characterized in terms of the capacity limits over a simplified channel model and are illustrated by means of practical examples and experimental results.