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Transmission transparency and potential convergence of optical network solutions at the physical layer for bit rates from 2.5 Gb·s-1 to 256 Gb·s-1
In this paper, we investigate optical network
recommendations GPON and XG-PON with triple-play
services in terms of physical reach, number of subscribers,
transceiver design, modulation format and implementation
cost. Despite trends to increase the bit
rate from 2.5 Gb s1 to 10 Gb s1 and beyond, TDMPONs
cannot cope with bandwidth requirements of future
networks. TDM and WDM techniques can be combined,
resulting in improved scalability. Longer physical
reach can be achieved by deploying active network
elements within the transmission path. We investigate
these options by considering their potential coexistence
at the physical layer. Subsequently, we analyse the upgrade
of optical channels to 100 Gb s1 and 256 Gb s1
by using advanced modulation formats, which combine
polarization division multiplexing with coherent detection
and digital signal processing. We show that PDMQPSK
format is suitable for 100 Gb s1 systems and
PDM-16QAM is more beneficial at 256 Gb s1. Simulations
are performed in the OptSim software environment
UDWDM-PON using low-cost coherent transceivers with limited tunability and heuristic DWA
A new Passive Optical Network (PON)
for access, making use of Ultra Dense Wavelength
Division Multiplexing (UDWDM) by densely spacing
channels at few GHz, and introducing the
“wavelength-to-the-user” concept, is proposed. The
key challenge will be developing low-cost coherent
transceivers, providing an excellent selectivity while
avoiding filters, and furnishing high sensitivity,
which will allow high splitting ratios, large number
of users and long distance reach. The Optical
Distribution Network (ODN) at the outside plant is
based on splitters and kept compatible with legacy
systems. Optical Network Unit (ONU) designs
realized with coherent transceivers using one or two
lasers are presented and the corresponding Optical
Line Terminal (OLT) architectures are introduced.
The ONUs at customer premises own lasers with
limited thermal tunability and their wavelengths are
randomly distributed in a band. By using heuristic
Dynamic Wavelength Assignment (DWA) schemes and
extending the original working band, the required
optical band is obtained and optimized. In activation
processes, ONU acceptances up to 99.9% are achieved.
Furthermore, in operation scenario under indoors
and also under outdoors environmental conditions,
ONU blocking probabilities below 0.1% and ONU
availability ratios (OARs) up to 99.9% are
demonstrated. The PON is dimensioned according to
the number of deployed users and system reach;
moreover, power safety and also fiber nonlinearities
constraints are evaluated, illustrating the
characteristics of the projected network. Finally, the
coexistence with legacy networks is discussed.Peer ReviewedPostprint (author's final draft
Flexible TDMA/WDMA passive optical network: energy efficient next-generation optical access solution
Photonic integration enabling new multiplexing concepts in optical board-to-board and rack-to-rack interconnects
New broadband applications are causing the datacenters to proliferate, raising the bar for higher interconnection speeds. So far, optical board-to-board and rack-to-rack interconnects relied primarily on low-cost commodity optical components assembled in a single package. Although this concept proved successful in the first generations of optical-interconnect modules, scalability is a daunting issue as signaling rates extend beyond 25 Gb/s. In this paper we present our work towards the development of two technology platforms for migration beyond Infiniband enhanced data rate (EDR), introducing new concepts in board-to-board and rack-to-rack interconnects.
The first platform is developed in the framework of MIRAGE European project and relies on proven VCSEL technology, exploiting the inherent cost, yield, reliability and power consumption advantages of VCSELs. Wavelength multiplexing, PAM-4 modulation and multi-core fiber (MCF) multiplexing are introduced by combining VCSELs with integrated Si and glass photonics as well as BiCMOS electronics. An in-plane MCF-to-SOI interface is demonstrated, allowing coupling from the MCF cores to 340x400 nm Si waveguides. Development of a low-power VCSEL driver with integrated feed-forward equalizer is reported, allowing PAM-4 modulation of a bandwidth-limited VCSEL beyond 25 Gbaud.
The second platform, developed within the frames of the European project PHOXTROT, considers the use of modulation formats of increased complexity in the context of optical interconnects. Powered by the evolution of DSP technology and towards an integration path between inter and intra datacenter traffic, this platform investigates optical interconnection system concepts capable to support 16QAM 40GBd data traffic, exploiting the advancements of silicon and polymer technologies
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