Showing papers by "Victor Polo published in 2016"

UDWDM-PON using low-cost coherent transceivers with limited tunability and heuristic DWA

Abstract: A new passive optical network (PON) for access, making use of ultra-dense wavelength division multiplexing (UDWDM) by densely spacing channels by a few gigahertz and introducing the "wavelength-to-the-user" concept, is proposed. The key challenge will be developing low-cost coherent transceivers that provide an excellent selectivity while avoiding filters and furnishing high sensitivity, which will allow high splitting ratios, large numbers of users, and long-distance reach. The optical distribution network (ODN) at the outside plant is based on splitters and is 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 the customer premises have lasers with limited thermal tenability, 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 scenarios under indoor and also under outdoor 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 non-linearities constraints are evaluated, illustrating the characteristics of the projected network. Finally, the coexistence with legacy networks is discussed.

Ultra-dense WDM access network field trial

Abstract: An UDWDM-PON with simple real-time ASK and DPSK transceivers at 6.25 GHZ channel spacing is validated in a field-trial with deployed fiber with power budget above 40 dB. This work presents final results of the Coconut European Project.

Monolithically Integrated Dual-Output DEML for Full Duplex DPSK-ASK and DPSK-SSB ONU in Ultra-Dense Channel Spaced Access Network

Abstract: Ultra-dense access network attracts people's attention recently; however, until now it is difficult to implement it commercially owing to cost, footprint, and the traditional complexity of coherent receiver. Single laser, especially integrated laser-based optical network unit (ONU) provides a potential system for simplifying the ONU. Here, we show a 2.5-Gb/s/user bidirectional transmission with 5-GHz channel spacing between uplink and downlink for ultra-dense wavelength division multiplexed. A monolithic integration on dual output dual electro-absorption modulated laser (DEML)-based ONU for “λ-to-the-user” network is demonstrated. Furthermore, bidirectional differential phase-shift keying (DPSK)-amplitude shift keying and DPSK-single side band transmission with low-footprint, monolithically integrated DEML at ONU are also tested.

First demonstration and field trial on multi-user UDWDM-PON full duplex PSK-PSK with single monolithic integrated dual-output-DFB-SOA based ONUs.

Abstract: We demonstrate a monolithically integrated dual-output DFB-SOA, and conduct the field trial on a multi-user bidirectional coherent ultradense wavelength division multiplexing-passive optical network (UDWDM-PON). To the best of our knowledge, this is the first achievement of simplified single integrated laser-based neighboring coherent optical network units (ONUs) with a 12.5 GHz channel spaced ultra-dense access network, including both downstream and upstream, taking the benefits of low footprint and low-temperature dependence.

Application on Minimizing Residual AM in DPSK UDWDM-PON ONU by Integrated Dual-EML

Abstract: A monolithically integrated dual electroabsorption modulated laser (DEML), consisting of distributed feedback laser (DFB) and electroabsorption modulator (EAM) sections, is proposed as a transmitter in an optical network unit with phase-shift keying (PSK) modulation. The DFB is directly modulated in phase, and the EAM section is applied for mitigating the residual amplitude modulation. The DEML, as compared with external phase modulator, has advantages of low cost, simplified design, low footprint, and reasonable power consumption, thus making it attractive for an ultradense wavelength division multiplexing passive optical unit. The system is validated at 2.5 and 5 Gb/s with intradyne detection.

Multilevel direct DFB phase modulation in 6.25 GHz spectrally spaced UDWDM PONs

Abstract: Direct phase modulation of DFB is demonstrated with DPSK, DQPSK and Duobinary modulation formats and detected with an intradyne receiver based on a 120-degree hybrid. The system is tested in a 50 km fibre link with 6.25 GHz channel spacing among users in a UDWDM-PON. By using higher modulation formats, the spectral efficiency can be increased in a single carrier system without spectral shaping while achieving an Rx sensitivity of −40 dBm at BER = 10−3 for 5 Gb/s in a 2 GHz bandwidth limited DFB.

Coherent ONU based on 850 μm-long cavity-RSOA for next-generation ultra-dense access network

Abstract: In this Letter, an efficient bidirectional differential phase-shift keying (DPSK)—DPSK transmission for a ultra-dense wavelength division-multiplexed passive optical network is proposed. A single distributed feedback laser at the optical network unit (ONU) is used both as the local laser for downlink coherent detection and the optical carrier for uplink. Phase-shift keying is generated using a low-cost reflective semiconductor optical amplifier (RSOA) at the ONU. The RSOA chip has the bandwidth of 4.7 GHz at the maximum input power and bias current. For uplink transmission, the sensitivity of the RSOA chip reaches −48.2 dBm at the level of bit error rate=10−3 for back-to-back, and the penalty for 50 km transmission is less than 1 dB when using polarization diversity.

Evaluating the energy efficiency of DWA algorithms in UDWDM-PONs

Abstract: Ultra-Dense Wavelength Division Multiplexing (UDWDM) has been proposed for the optical access Passive Optical Network (PON) in the COst-effective COhereNt Ultra-dense-WDM-PON for lambda-To-the-user access (COCONUT) project, introducing the wavelength-to-the-user concept. A low-cost high sensitivity coherent detection technique furnishes high splitting ratios and long-reach extension. ONU coherent transceivers employ lasers with wavelengths randomly distributed and densely spaced in the optical band, but owning limited tunability. The wavelength channels are allocated using heuristic Dynamic Wavelength Assignment (DWA) algorithms. These schemes are applied not only in activation processes, but also during operation under environmental conditions, adapting the laser tuning to provide the required assigned channel. The laser tuning is achieved by heating or cooling control, and the power consumption varies depending on the wavelength position in a tuning window. We evaluate and compare the power consumption of the developed DWA schemes in the network, as energy efficiency is important to reduce the green-house gas emissions.