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  • Experimental evaluation and improvement methods for low cost transmitters in long reach PONs

     Chatzi, Sotiria; Klonidis, Dimitrios; Tsekrekos, Christos P.; Lazaro Villa, Jose Antonio; Prat Goma, Josep; Tomkos, Ioannis
    Optical fiber technology
    Date of publication: 2013-12
    Journal article

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    An extensive experimental research of an optical access network behaviour has been realized, in the framework of studying distance enhancement of long reach passive optical networks (PONs), while maintaining low cost and high performance. The network system has been implemented with low cost transmitters - operated at low driving voltage, without the use of electrical amplification, at 10 Gb/s - and with colourless optical network units (ONUs) as receivers. Although studied for variable lengths, error-free transmission (target bit-error rate at 10-9) over 100 km reach has been achieved in several ways. The performance of extended PONs, when low cost transmitters operated at low driving voltage are utilized, is improved by the application of optical dispersion compensation and electronic equalization techniques. The chirp of the transmitter has been shown to have an important effect on the behaviour of the system because of the dispersion phenomenon. It is observed however, that the combined use of optical dispersion compensation and electronic equalization gives a reduction of 5-10 dB of the required optical signal to noise ratio (OSNR) for an error-free transmission. Moreover, it significantly reduces the heterogeneity of the system performance for several distances, yielding a predictable behaviour, while at the same time permits the use of handy, inexpensive and integrated transmitters. © 2013 Elsevier Inc. All rights reserved.

  • OPTIMIZATION OF EMERGING EXTENDED FTTH WDM/TDM PONS AND FINANCIAL OVERALL ASSESSMENT  Open access

     Chatzi, Sotiria
    Defense's date: 2013-11-26
    Department of Signal Theory and Communications, Universitat Politècnica de Catalunya
    Theses

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    Les tecnologies d¿accés òptic han experimentat un boom als últims anys, gracies a la migració continua del serveis que s¿ofereixen mitjançant Internet. Encara que les tecnologies emprades per implementar el Fiber-to-the-X (FTTX) y Fiber-to-the-Home (FTTH) estan basades majoritàriament en Active solutions o amb Passive Optical Networks (PONs), amb Time Division Multiplexing (TDM), es poden apreciar una evolució cap a solucions hibrides com per exemple Wavelength Division Multiplexing/Time Division Multiplexing (WDM/TDM). El que te que ser investigat i finalment establert són els dissenys exactes per aquest important canvi cap a l¿integració, que ha de ser optimitzada en termes de qualitat de transmissió i cost, per poder afrontar tots els requisits de xarxes òptiques passives de nova generació.Com a punts crítics, el disseny i cost són els principals punts de discussió. Els mateixos cobreixen una amplia gama i inclouen l¿estimació de costos de diverses xarxes de tecnologies òptiques ¿ arquitectures i les seves corresponents comparacions, a més de revisar l¿optimització del seu disseny. En aquesta última categoria, l¿amplificació remota en línia, l¿ús d¿una freqüència de banda alternativa i estesa, compensació de la dispersió i tècniques d¿equalització han estat examinades així com una combinació dels mitjans abans esmentats d¿optimització de xarxes.Juntament amb la proba principal de les característiques proposades, el beneficis han estat ressaltats en els diferents estudis del cas, al mateix temps que els dissenys més representatius s¿han examinat a fons.

    Optical access technology has experienced a boost in the last years, thanks to the continuously migrating multimedia services that are offered over the internet. Though the technologies used for deploying Fiber-To-The-x (FTTx) and Fiber-to-the-Home (FTTH) are mostly based on either Active solutions or as far as Passsive Optical Networks (PONs) is concerned, in Time Division Multiplexing (TDM), an evolution towards Hybrid solutions such as Wavelength Division Multiplexing/Time Division Multiplexing (WDM/TDM) can be foreseen. What needs to be researched and finally established are the exact designs for this important step of integration, which should be optimized in terms of transmission performance and cost, to address all requirements of next-generation passive optical networks. As the most critical elements in optical access network, the design and its cost are the main topics of this discussion. The covered topics span over a wide range and include cost estimation of several optical network technologies - architectures and their comparison and furthermore, subjects of design optimization. In this last category, in-line remote amplification, use of an alternative and an extended frequency band, dispersion compensation and equalization techniques have been examined as well as a combination of the aforementioned means of network optimization. Next to the principal proof of the proposed techniques, the benefits are highlighted in different case studies, while the most representative designs are further discussed.

  • WDM/TDM PON Bidirectional Networks Single-Fiber/Wavelength RSOA-based ONUs Layer 1/2 Optimization  Open access

     López Pastor, Eduardo Tommy
    Defense's date: 2013-09-12
    Department of Signal Theory and Communications, Universitat Politècnica de Catalunya
    Theses

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    Esta Tesis propone un rediseño y optimización de tres arquitecturas de redes PON: WDM-PON, TDM-PON y un hibrido WDM/TDM PON al nivel de capa PHY y capa MAC, en términos de mínimo costo de implementación y mejor performance en un escenario orientado a Greenfield NG-PON. En particular, una red WDM/TDM PON con ONU reflectiva, basad en RSOA, y operando sobre una fibra/una longitud de onda, es el escenario de optimización propuesto.En redes WDM-PON y TDM-PON, relevantes parámetros son optimizados. Un profundo análisis del comportamiento del efecto Rayleigh Backscattering, el principal problema en este tipo de escenarios, es analizado en modo de transmisión continuo y en modo burst, para mejorar la performance de estas arquitecturas. Como consecuencia, un nuevo modelo matemático para este fenómeno en modo burst es presentado, por primera vez, por este trabajo.Además, una red ¿cost-effective¿ y de simple diseño basada en SCM WDM/TDM PON con ONU reflectiva fue optimizada e implementada. Este prototipo mostro satisfactoria performance, confiabilidad, robustez y versatilidad, y es capaz de dar cobertura hasta a 1280 usuarios a 2.5 Gb/s / 1.25 Gb/s en downstream/upstream, sobre 20 Km, manteniendo compatibilidad con el estándar GPON de la ITU-T.Este precedente ha permitido a la red SARDANA extender el diseño a una arquitectura de largo alcance metro-access (100 km). Una propuesta de capa MAC, basada en el rediseño de la sub-capa Transmission Convergence para una red de largo alcance (metro-access), más ágil y de mejor performance es presentado como una relevante contribución de este trabajo.

    This Thesis proposes the design and the optimization of a hybrid WDM/TDM PON at the L1 (PHY) and L2 (MAC) layers, in terms of minimum deployment cost and enhanced performance for Greenfield NGPON. The particular case of RSOA-based ONUs and ODN using a single-fibre/single-wavelength is deeply analysed. In this WDM/TDM PON relevant parameters are optimized. Special attention has been given at the main noise impairment in this type of networks: the Rayleigh Backscattering effect, which cannot be prevented. To understand its behaviour and mitigate its effects, a novel mathematical model for the Rayleigh Backscattering in burst mode transmission is presented for the first time, and it has been used to optimize the WDM/TDM RSOA based PON. Also, a cost-effective, simple design SCM WDM/TDM PON with rSOA-based ONU, was optimized and implemented. This prototype was successfully tested showing high performance, robustness, versatility and reliability. So, the system is able to give coverage up to 1280 users at 2.5 Gb/s / 1.25 Gb/s downstream/upstream, over 20 Km, and being compatible with the GPON ITU-T recommendation. This precedent has enabled the SARDANA network to extend the design, architecture and capabilities of a WDM/TDM PON for a long reach metro-access network (100 km). A proposal for an agile Transmission Convergence sub-layer is presented as another relevant contribution of this work. It is based on the optimization of the standards GPON and XG-PON (for compatibility), but applied to a long reach metro-access TDM/WDM PON rSOA-based network with higher client count. Finally, a proposal of physical implementation for the SARDANA layer 2 and possible configurations for SARDANA internetworking, with the metro network and core transport network, are presented.

  • Monitorización y control remoto de consumo energético mediante comunicación Wifi

     Ortega Gómez, Isidre; Zarza Sánchez, Sergio; Lazaro Villa, Jose Antonio; Fernandez Canti, Rosa M.
    Jornadas de Automática
    Presentation's date: 2013-09-04
    Presentation of work at congresses

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  • Optimal trade-off for a bidirectional single-fibre single-wavelength TDM-PON rSOA-based ONU

     López Pastor, Eduardo Tommy; Polo Querol, Victor Manuel; Lazaro Villa, Jose Antonio; Prat Goma, Josep
    International Conference on Transparent Optical Networks
    Presentation's date: 2013-06
    Presentation of work at congresses

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    In this paper, an optimal trade-off between the Optical Distribution Network (ODN) power budget and the upstream optical Signal-to-Rayleigh Ratio (US-oSRR), for a Single- Fibre/Wavelength TDM-PON rSOA-based ONU network is presented. Up to 32 ONUs can be reached over a practical implementation. Burst operation is considered.

    In this paper, an optimal trade-off between the Optical Distribution Network (ODN) power budget and the upstream optical Signal-to-Rayleigh Ratio (US-oSRR), for a Single- Fibre/Wavelength TDM-PON rSOA-based ONU network is presented. Up to 32 ONUs can be reached over a practical implementation. Burst operation is considered.

  • Flexible WDM/FTDM passive optical network with RZ-seeded all-optical sub-wavelength grid engine

     Schrenk, Bernhard; Katopodis, Vasilis; Bauwelinck, Johan; Lazaro Villa, Jose Antonio; Yin, Xin; Bakopoulos, Paraskevas; Spyropoulou, Maria; Qiu, Xing Z.; Avramopoulos, Hercules
    Optical Fiber Communication Conference and Exposition and National Fiber Optic Engineers Conference
    Presentation's date: 2013-03
    Presentation of work at congresses

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    All-optical FDM grid generation and channel selection is experimentally demonstrated through optical signal processing. Full-duplex 10G/210G transmission with reflective ONUs is validated for 20dB budget and 25km reach. An optional 10Gb/s FDM/TDM mode is verified.

    All-optical FDM grid generation and channel selection is experimentally demonstrated through optical signal processing. Full-duplex 10G/2×10G transmission with reflective ONUs is validated for 20dB budget and 25km reach. An optional 10Gb/s FDM/TDM mode is verified.

  • Digitally processed modulation formats and integrated photonics for flexible optical metro-access networks

     Lazaro Villa, Jose Antonio; Schrenk, Bernhard; Malligaraj, M.; Cano Valadez, Ivan Nicolas; Parra, M.; Sridharan, Madanagurusamy; Junyent Giralt, Gabriel
    International Conference on Transparent Optical Networks
    Presentation's date: 2013-06-23
    Presentation of work at congresses

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    Digitally processed modulations formats such as Nyquist-WDM are investigated for implementation of future flexible optical networks, by using integrated photonic devices and moderate speed optoelectronics. We compare with other modulation formats as OFDM regarding complexity and adaptability to transceiver limitations.

  • Area and laser power scalability analysis in photonic networks-on-chip

     Abadal Cavalle, Sergi; Cabellos Aparicio, Alberto; Lazaro Villa, Jose Antonio; Nemirovsky, Mario; Alarcon Cot, Eduardo Jose; Sole Pareta, Josep
    International Conference on Optical Network Design and Modeling
    Presentation's date: 2013-04-18
    Presentation of work at congresses

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    In the last decade, the field of microprocessor architecture has seen the rise of multicore processors, which consist of the interconnection of a set of independent processing units or cores in the same chip. As the number of cores per multiprocessor increases, the bandwidth and energy requirements for their interconnection networks grow exponentially and it is expected that conventional on-chip wires will not be able to meet such demands. Alternatively, nanophotonics has been regarded as a strong candidate for chip communication since it could provide high bandwidth with low area and energy footprints. However, issues such as the unavailability of efficient on-chip light sources or the difficulty of implementing all-optical buffering or header processing hinder the development of scalable photonic on-chip networks. In this paper, the area and laser power of several photonic on-chip network proposals is analytically modeled and its scalability is evaluated. Also, a graphene-based hybrid approach is presented

    In the last decade, the field of microprocessor architecture has seen the rise of multicore processors, which consist of the interconnection of a set of independent processing units or cores in the same chip. As the number of cores per multiprocessor increases, the bandwidth and energy requirements for their interconnection networks grow exponentially and it is expected that conventional on-chip wires will not be able to meet such demands. Alternatively, nanophotonics has been regarded as a strong candidate for chip communication since it could provide high bandwidth with low area and energy footprints. However, issues such as the unavailability of efficient on-chip light sources or the difficulty of implementing all-optical buffering or header processing hinder the development of scalable photonic on-chip networks. In this paper, the area and laser power of several photonic on-chip network proposals is analytically modeled and its scalability is evaluated. Also, a graphene-based hybrid wireless/optical-wired approach is presented, aiming at enabling end-to-end photonic on-chip networks to scale beyond thousands of cores

  • Phase modulated optical OFDM upstream with IM/DD downstream for full-duplex 10 Gb/s bidirectional transmission over a single wavelength with a reflective SOA

     Fàbrega, Josep Maria; Chochol, Marcin; Svaluto Moreolo, Michela; Lazaro Villa, Jose Antonio; Junyent Giralt, Gabriel
    International Conference on Transparent Optical Networks
    Presentation's date: 2013-06
    Presentation of work at congresses

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    The feasibility of a phase modulated optical OFDM upstream transmission employing IM/DD downstream for achieving a bidirectional transmission with symmetric data rate of 10 Gb/s over a single wavelength is investigated for a passive optical access network scenario. Upstream modulation is performed using a reflective semiconductor amplifier, and coherent detection is employed at the central office. The system performance is assessed in terms of transmission distance and possible back-reflections.

    The feasibility of a phase modulated optical OFDM upstream transmission employing IM/DD downstream for achieving a bidirectional transmission with symmetric data rate of 10 Gb/s over a single wavelength is investigated for a passive optical access network scenario. Upstream modulation is performed using a reflective semiconductor amplifier, and coherent detection is employed at the central office. The system performance is assessed in terms of transmission distance and possible back-reflections.

  • Demonstration of a remotely dual-pumped long-reach PON for flexible deployment

     Schrenk, Bernhard; Lazaro Villa, Jose Antonio; Klonidis, Dimitrios; Bonada Bo, Francesc; Saliou, Fabienne; Polo Querol, Victor Manuel; López Pastor, Eduardo Tommy; Le, Q.T.; Chanclou, Philippe; Costa, L; Teixeira, A.; Chatzi, Sotiria; Tomkos, Ioannis; TosiBeleffi, Giorgio M; Leino, D.; Soila, Risto; Spirou, S; de Valicourt, Guilhem; Brenot, Romain; Kazmierski, Christophe; Prats, Jordi
    Journal of lightwave technology
    Date of publication: 2012-04-01
    Journal article

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    We propose and experimentally demonstrate a flexible wavelength division multiplexing/time division multiplexing network architecture for converged metro-access environment. Entire passiveness in the fiber plant is achieved with remote amplification in the signal distribution nodes along the metro ring and in the power splitters of the local access tree. We assist a traditional remote pumping scheme with a distributed pump provided by the optical network units and demonstrate that loss budgets beyond 30 dB can be supported. Data transmission of up to 10 Gb/s is evaluated in different deployment scenarios, reaching from a 78 km long reach rural to a dense 1:128 split/ urban configuration with field installed fibers, including also worst case resilience configurations.

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    An Open source multiplatform virtual laboratory for engineering education  Open access

     Fernandez Canti, Rosa M.; Lazaro Villa, Jose Antonio; Zarza Sánchez, Sergio; Villar Zafra, Aitor
    International journal of online engineering
    Date of publication: 2012-11
    Journal article

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    An autonomous and multiplatform virtual laboratory for educational purposes is presented. The implemented platform includes a server with a SSH (Secure SHell) connection and a separated repository containing the virtual experiments. The programming of the experiments is implemented in Java language based tool, the EJS (Easy Java Simulation) and uses an external computation engine, for example Matlab. The virtual laboratory provides control system experiments at University level. Two application examples are described, namely, a magnetic levitator and an inverted pendulum-cart system. The virtual laboratory has been successfully used for education and training of Electronics Engineering students. A discussion of the results of this e-learning experience is also presented.

  • Quaternary TDM-PAM as upgrade path of access PON beyond 10Gb/s

     Verbrugghe, Jochen; Schrenk, Bernhard; Bauwelinck, Johan; Yin, Xin; Dris, Stefanos; Lazaro Villa, Jose Antonio; Katopodis, Vasilis; Bakopoulos, Paraskevas; Avramopoulos, Hercules
    Optics express
    Date of publication: 2012-12-10
    Journal article

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    A 20 Gb/s quaternary TDM-PAM passive optical network with chirped and non-linear optical transmitters is experimentally demonstrated. The migration from legacy TDM-PONs and the implications of using available 10 Gb/s components are analyzed. We show that a loss budget of 27.3 dB is compatible together with a packet power ratio of 10 dB between loud and soft optical network units

  • Graphene-enabled hybrid architectures for multiprocessors: bridging nanophotonics and nanoscale wireless communication

     Abadal Cavalle, Sergi; Cabellos Aparicio, Alberto; Lazaro Villa, Jose Antonio; Alarcon Cot, Eduardo Jose; Sole Pareta, Josep
    International Conference on Transparent Optical Networks
    Presentation's date: 2012-07-04
    Presentation of work at congresses

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  • Digital Nyquist WDM for access networks using limited bandwidth reflective semiconductor optical amplifiers

     Lazaro Villa, Jose Antonio; Knorr, Sebastian; Schrenk, Bernhard; Cano Valadez, Ivan Nicolas; Polo Querol, Victor Manuel; Prat Goma, Josep; Carena, Andrea; Bosco, Gabriella
    Optical Fiber Communication Conference and Exposition and National Fiber Optic Engineers Conference
    Presentation's date: 2012
    Presentation of work at congresses

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    Digital Nyquist-WDM is experimentally demonstrated using RSOA-based colorless ONUs, providing a 6-fold enhancement of transmission capacity through 25km fiber, and showing digital Nyquist-WDM as promising candidate for cost-effective flexible bandwidth allocation in PONs.

    Digital Nyquist-WDM is experimentally demonstrated using RSOA-based colorless ONUs, providing a 6-fold enhancement of transmission capacity through 25km fiber, and showing digital Nyquist-WDM as promising candidate for cost-effective flexible bandwidth allocation in PONs.

  • Quaternary TDM-PAM and its implications for TDMA equipment

     Dris, Stefanos; Bauwelinck, Johan; Yin, Xin; Schrenk, Bernhard; Lazaro Villa, Jose Antonio; Katopodis, Vasilis; Bakopoulos, Paraskevas; Verbrugghe, Jochen; Avramopoulos, Hercules
    European Conference and Exhibition on Optical Communication
    Presentation of work at congresses

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    The migration towards a 20 Gb/s quaternary TDM-PAM passive optical network with chirped and non-linear optical transmitters is experimentally studied. We show that a loss budget of 27.3 dB is compatible together with a packet power ratio of 10 dB between loud and soft ONU

    The migration towards a 20 Gb/s quaternary TDM-PAM passive optical network with chirped and non-linear optical transmitters is experimentally studied. We show that a loss budget of 27.3 dB is compatible together with a packet power ratio of 10 dB between loud and soft ONU

  • Full-duplex 20/10 Gb/s WDM-PON with remodulation of chirped ASK and multi-level quaternary PAM and OFDM

     Lazaro Villa, Jose Antonio; Schrenk, Bernhard; Maziotis, Alexandros; Cano Valadez, Ivan Nicolas; Bakopoulos, Paraskevas; Prat Goma, Josep; Avramopoulos, Hercules
    Optical Fiber Communication Conference and Exposition and National Fiber Optic Engineers Conference
    Presentation's date: 2012-03
    Presentation of work at congresses

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    A full-duplex 20/10Gb/s WDM-PON is demonstrated by all-optical carrier recovery technique, showing that it is efficient and flexible for being applied to different downstream signals as non-/chirped ASK or multilevel signals as 4-PAM or OFDM

    A full-duplex 20/10Gb/s WDM-PON is demonstrated by all-optical carrier recovery technique, showing that it is efficient and flexible for being applied to different downstream signals as non-/chirped ASK or multilevel signals as 4-PAM or OFDM

  • Network dimensioning for a TDM-PON deployment Single-fibre single-wavelength-reuse based on reflective ONUs

     López Pastor, Eduardo Tommy; Polo Querol, Victor Manuel; Lazaro Villa, Jose Antonio; Prat Goma, Josep
    International Conference on Transparent Optical Networks
    Presentation's date: 2012
    Presentation of work at congresses

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    The network dimensioning for a TDM-PON deployment based on reflec tive ONUs is presented in order to optimize number of users for efficient exploitation. Due to wavelength reuse, the study is focused on the power budget and DS-ER/US-oSRR critical relation. These and other parameters are analyzed theoretical and experimentally and optimal design values are presented. A TDM-PON for 32 users/20km is possible at BER = 5E-4 reference level.

  • Upstream performance improvement of low cost 10Gb/s ONUs with centralized OLT equalizer and FEC

     Cano Valadez, Ivan Nicolas; Porto, S.; Naughton, A.; Ossieur, P.; Townsend, P.D.; Lazaro Villa, Jose Antonio; Prat Goma, Josep
    International Conference on Transparent Optical Networks
    Presentation's date: 2012
    Presentation of work at congresses

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    An access optical network based on 10Gb/s DML and R-EAM-SOA as transmitters was experimentally tested with a centralized MLSE equalizer to compensate for the chirp, dispersion and RB. Several scenarios were studied and results indicate that the fibre distance reach can be improved by 50% with the use of MLSE and FEC.

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    Laboratorio virtual multiplataforma para educación en ingeniería  Open access

     Fernandez Canti, Rosa M.; Lazaro Villa, Jose Antonio; Villar Zafra, Aitor; Zarza Sánchez, Sergio
    Jornada Innovació Docent UPC
    Presentation's date: 2012-07-05
    Presentation of work at congresses

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    Se presenta un laboratorio virtual autónomo y multiplataforma para docencia. La plataforma implementada incluye un servidor con conexión SSH (Secure SHell) y un repositorio separado que contiene los experimentos virtuales. La programación de los experimentos se ha realizado en Java usando la herramienta EJS (Easy Java Simulation) para entornos gráficos y el programa Matlab como motor de cálculo externo. El laboratorio virtual contiene experimentos de control a nivel universitario. Se presentan dos ejemplos de aplicación, en concreto, un levitador magnético y un sistema de péndulo invertido con carrito. El laboratorio virtual ha sido probado con éxito en la formación de estudiantes de Ingeniería Electrónica. Se presentan y comentan los resultados de esta experiencia de e-learning. ABSTRACT An autonomous and multiplatform virtual laboratory for educational purposes is presented. The implemented platform includes a server with a SSH (Secure SHell) connection and a separated repository containing the virtual experiments. The programming of the experiments is implemented in Java language developed by means the EJS (Easy Java Simulation) tool and uses the Matlab language as an external computation engine. The virtual laboratory provides control experiments at University level. Two application examples are described, namely, a magnetic levitator and an inverted pendulum-cart system. The virtual laboratory has successfully been used for education and training of Electronics Engineering students. A discussion of the results of this e-learning experience is also presented.

  • Multiplatform virtual laboratory for engineering education

     Villar Zafra, Aitor; Zarza Sánchez, Sergio; Lazaro Villa, Jose Antonio; Fernandez Canti, Rosa M.
    International Conference on Remote Engineering and Virtual Instrumentation
    Presentation's date: 2012-07
    Presentation of work at congresses

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    An autonomous and multi platform virtual laboratory for educational purposes is presented. The implemented platform includes a server with a SSH(Secure SHeil)connection and a separated repository containing the virtual experiments. The programming of the experiments is implemented in Java language based tool, the EJS (Easy Java Simulation) and uses an external computation engine, for example MatIab. The virtual laboratory provides control system experimentsat University level. Two application examples are described, namely, a magnetic levitator and an inverted pendulum­ cart system. The virtual laboratory has been successfully used for education and training of Electronics Engineering students. A discussion of the results of this e-learning experience is also presented.

  • High customer density PON with passive amplification through distributed pump for > 1:1000 tree split

     Schrenk, Bernhard; Bauwelinck, Johan; Bonada Bo, Francesc; Lazaro Villa, Jose Antonio; Xing-Zhi, Qiu; Chanclou, Philippe; Prat, Jordi
    Journal of lightwave technology
    Date of publication: 2011-07-01
    Journal article

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    A network architecture for tree-like passive optical networks (PONs) with high splitting ratios is proposed and experimentally demonstrated. Splits >1000 are shown to be feasible thanks to a noise-powered amplifier that is built-in inside the power splitter. The proposed noise pumping technique recycles the natural amplified spontaneous emission (ASE) of a semiconductor optical amplifier at the customer premises, avoiding the use of an electrical power supply in the fiber plant. The impact of the location of this noise-powered extender box inside the signal distribution element of the tree is analyzed in terms of obtained signal gain, ASE accumulation among multiple extender boxes, and transmission performance. Finally, full-duplex transmission at 10 Gb/s with burst-mode upstream is demonstrated in a particular scenario with a split of 1:1000 and a loss budget of 39.5 dB, revealing that power margins >3 of dB can be provided.

  • An all-optical carrier recovery scheme for access networks with simple ASK modulation

     Schrenk, Bernhard; Bakopoulos, Paraskevas; Kehayas, E.; Maziotis, Alexandros; Lazaro Villa, Jose Antonio; Avramopoulos, Hercules; Prat Goma, Josep
    Journal of optical communications and networking
    Date of publication: 2011-09
    Journal article

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    We theoretically investigate and experimentally demonstrate a scheme for all-optical carrier recovery in loopback access networks that avoids orthogonal or complex modulation formats for the downstream or upstream signals. The applied technique is based on a passive resonating circuit that is capable of recovering the optical carrier of the amplitude-shift-keyed downstream signal for remodulation with a reflective modulator as upstream transmitter enabling full-duplex 10 Gb/s operation. The scheme is compared with alternative pattern suppression techniques based on optical gain saturation and electro-optical feed-forward injection for the stringent requirements of next-generation access networks, namely, an extended loss budget and high upstream data rates. Operation at downstream modulation depths of ~3 dB is reported with the feed-forward approach, while higher modulation depths of up to 9 dB are demonstrated with the all-optical carrier recovery technique, for which the dependence on longer sequences of consecutive identical bits is investigated. Finally, the feasibility of the all-optical downstream cancelation technique for optical access networks is evaluated in a wavelength division multiplexed passive optical network, showing full-duplex transmission with margins of at least 9 dB.

  • Colorless ONU with all-optical clock recovery for full-duplex dense WDM PONs

     Maziotis, Alexandros; Schrenk, Bernhard; Bakopoulos, Paraskevas; Spyropoulou, Maria; Lazaro Villa, Jose Antonio; Prat Goma, Josep; Avramopoulos, Hercules
    IEEE photonics technology letters
    Date of publication: 2011-10-05
    Journal article

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  • Dual-operability and bandwidth partitioning enabled by an ONU with tandem-modulator

     Schrenk, Bernhard; Bauwelinck, Johan; Lazaro Villa, Jose Antonio; Kazmierski, Christophe; Xing-Zhi, Qiu; Prat Goma, Josep
    Journal of optical communications and networking
    Date of publication: 2011-09
    Journal article

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    An upgrade at the physical layer regarding unbundling and dynamic bandwidth provisioning of a wavelength division multiplexed access network is presented. The capability of a reflective modulator to act as a photodetector is exploited and allows a tandem configuration to be used at the optical network unit (ONU) for flexible switching of the detection and modulation branch. Consequently, a mechanism for service operator selection and for dynamic bandwidth partitioning up to twice the nominal data rate is provided. The scheme is experimentally evaluated for different kinds of modulators and shows, together with a full-duplex transmission at 10 Gb/s, additional operation modes, featuring unidirectional downstream and upstream burst-mode transmission with up to 20 Gb/s for ONUs based on a combination of a semiconductor optical amplifier and a reflective electro-absorption modulator.

  • C + L band extended reach amplified next generation access networks

     Girão, J.P.; Neto, B.; Rocha, A.M.; Reis, Catarina; Dionisio, R.P; Chatzi, Sotiria; Bonada Bo, Francesc; Lazaro Villa, Jose Antonio; Teixeira, A.L.J.; Andre, P. S
    Microwave and optical technology letters
    Date of publication: 2011-07
    Journal article

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    The feasibility of optical amplification solutions for extended reach next generation access networks in C + L bands is studied. Amplification schemes based on Raman fiber amplifier and their combination with remotely pumped erbium-doped fiber amplifiers are assessed and optimized. The results concerning a ring with 80 km for rural scenario demonstrate gain equalization over a bandwidth of 50 nm. The survey was complemented with experimental results

  • Modulated Grating Y-Structure Tunable Laser for gamma-Routed Networks and Optical Access

     Fabrega Sanchez, Josep Maria; Schrenk, Bernhard; Bonada Bo, Francesc; Lazaro Villa, Jose Antonio; Forzati, Marco; Jean Rigole,, Pierre; Prat Goma, Josep
    IEEE journal on selected topics in quantum electronics
    Date of publication: 2011-12-05
    Journal article

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  • Energy-efficient optical access networks supported by a noise-powered extender box

     Schrenk, Bernhard; Bonada Bo, Francesc; Bauwelinck, Johan; Prat Goma, Josep; Lazaro Villa, Jose Antonio
    IEEE journal on selected topics in quantum electronics
    Date of publication: 2011-03
    Journal article

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  • Power efficiency of SARDANA and other long-reach optical acces networks  awarded activity

     Lovric, Ana; Aleksic, Slavisa; Lazaro Villa, Jose Antonio; Tosi Beleffi, Giorgio; Prat Goma, Josep; Polo Querol, Victor Manuel
    International Conference on Optical Networking Design and Modeling
    Presentation's date: 2011
    Presentation of work at congresses

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    Different long-reach optical access networks are studied with respect to their power efficiency. Special focus is dedicated to the hybrid TDM/WDM PON proposed in the SARDANA project, in which remote amplification is utilized for reach extension. The structures of the remote nodes and subsystems for reach extension are shown and discussed. The influence of uplink capacity limitation on power efficiency is evaluated, i.e., the access networks' efficiencies are presented for different CO capacities in terms of Watt per user and per Gbit/s of user's bandwidth as a function of number of users connected to the CO. The results show remarkable power efficiency degradation for high-speed access technologies in case of strong uplink limitation, while for unlimited uplink case, 10G-EPON and SARDANA networks show the best efficiency.

  • Wavelength-tuneable remote node for enhanced resilience and optimization of WDM access networks

     Bonada Bo, Francesc; Schrenk, Bernhard; Costa, Liliana; Teixeira, Marco Antonio; Chatzi, Sotiria; Klonidis, Dimitrios; Tomkos, Ioannis; Prat Goma, Josep; Lazaro Villa, Jose Antonio
    International Conference on Transparent Optical Networks
    Presentation's date: 2011
    Presentation of work at congresses

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    A remote node design with a wavelength tuneable optical add/drop element is presented and experimentally demonstrated for application in a resilient ring+tree access network architecture. The flexibility of the network node regarding its allocation to the wavelength dimension of the network can be exploited to retain service delivery in case of subsystem failure at the optical line terminal (OLT) or optical network unit (ONU) as well as for an optimization of the transmission performance when switching from normal to resilient network operation in case of a ring fibre cut. A loss budget of 30 dB is compatible for the passive optical access network.

  • Techno-economics of resilient extended FTTH PONs

     Prat Goma, Josep; Lazaro Villa, Jose Antonio; Chatzi, Sotiria; Tomkos, Ioannis
    International Conference on Transparent Optical Networks
    Presentation's date: 2011-06-30
    Presentation of work at congresses

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    This work analyses different architectures of protected FTTH passive optical networks in terms of device and infrastructure requirements and costs, considering different home density scenarios and volume projections. The results show that the Sardana hybrid resilient network presents a wider scalability range in terms of cost efficiency.

  • Optical subsystems for next generation access networks

     Lazaro Villa, Jose Antonio; Polo Querol, Victor Manuel; Schrenk, Bernhard; Bonada Bo, Francesc; Cano Valadez, Ivan Nicolas; López Pastor, Eduardo Tommy; Kazmierski, Christophe; de Valicourt, Guilhem; Brenot, Romain; Bauwelinck, Johan; Xing-Zhi, Qiu; Ossieur, P.; Forzati, Marco; Rigole, Jean-Pierre; Monroy, I.T; Tangdiongga, E.; Morant, Maryland; Nicolau, L.; Teixeira, A.L.; Erasme, D.; Klonidis, Dimitrios; Tomkos, Ioannis; Prat Goma, Josep; Kouloumentas,, Christos; Avramopoulos, Hercules
    Advanced Photonics Congress Access Networks and In-house Communications
    Presentation's date: 2011-06-12
    Presentation of work at congresses

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    Recent optical technologies are providing higher flexibility to next generation access networks: on the one hand, providing progressive FTTx and specifically FTTH deployment, progressively shortening the copper access network; on the other hand, also opening fixed-mobile convergence solutions in next generation PON architectures. It is provided an overview of the optical subsystems developed for the implementation of the proposed NG-Access Networks.

  • Characterization and desing of multifunction photonic devices for next-generation fiber-to-the-home optical network units  Open access

     Schrenk, Bernhard
    Defense's date: 2011-04-28
    Department of Signal Theory and Communications, Universitat Politècnica de Catalunya
    Theses

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    El estudio e investigación en el campo de las redes ópticas de acceso han sido fomentadas en años recientes debido a la continua migración de Servicios multimedia que son ofrecidos a través de Internet. Aunque los dispositivos utilizados para implementar Fiber-to-the-Home (fibra a casa), que reemplazan las soluciones tradicionales basadas en cable de cobre, están basadas aún en micro-óptica, se puede prever una evolución hacia integración fotónica. Todavía queda la pregunta acerca de los diseños necesarios para este paso importante de integración, que debe ser optimizado en términos del desempeño de transmisión, eficiencia energética y costo con el fin de lograr todos los requerimientos de las redes fotónicas de siguiente generación. Como elemento más crítico en las redes de acceso ópticas es el equipo en los clientes, este trabajo se centra en éste. Los temes cubiertos abarcan una gama amplia e incluyen: el reciclado de longitudes de onda para transmisión de datos en full-dúplex a través de una sola frecuencia óptica; la generación de formatos de modulación avanzados con moduladores semiconductores de bajo costo y factor pequeño de integración; soporte de amplificación óptica a través de técnicas de sembrado y el soporte de funcionalidades de capes superiores en la capa física. Después de la prueba principal de las técnicas propuestas, se resaltan los beneficios, impedimentos y caminos de reemplazo hacia sistemas fotónicos multifuncionales a través de casos de estudio. Por su parte, los diseños más representativos se profundizan más sobre todo por su posibilidad de ser integrados fotónicamente.

    Optical access technology has experienced a boost in the last years, thanks to the continuously migrating multimedia services that are offered over the internet. Though the devices used for deploying Fiber-to-the-Home instead of traditional copper-based solutions are still based on micro-optics, an evolution towards photonic integration can be foreseen. What remains is the question about the exact designs for this important step of integration, which should be optimized in terms of transmission performance, energy efficiency and cost to address all requirements of next-generation photonic networks. As the most critical element in optical access, the customer premises equipment is in primary focus of this discussion. The covered topics span over a wide range and include wavelength recycling for full-duplex data transmission on a single optical frequency, the generation of advanced modulation formats with low-cost semiconductor modulators with small form factor, support for optical amplification by means of seeding techniques and the support of higher layer functionality at the physical layer. Next to the principal proof of the proposed techniques, the benefits, impediments and upgrade paths towards multifunctional photonic systems are highlighted in different case studies, while the most representative designs are further discussed in their capability of being photonically integrated.

  • All-Optical Intra-PON Data Routing Between ONUs with a MG-Y Tunable Laser as 2.5 Gbps Burst-Mode Transmitter

     Bonada Bo, Francesc; Schrenk, Bernhard; Fabrega Sanchez, Josep Maria; Lazaro Villa, Jose Antonio; Forzati, Marco; Jean Rigole,, Pierre; Prat Goma, Josep
    Optical Fiber Communication Conference and Exposition and National Fiber Optic Engineers Conference
    Presentation's date: 2011-03
    Presentation of work at congresses

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  • SOA/REAM as Vector Modulator for QAM Upstream

     Schrenk, Bernhard; Fabrega Sanchez, Josep Maria; Kazmierski, Christophe; Lazaro Villa, Jose Antonio; Prat Goma, Josep
    Optical Fiber Communication Conference and Exposition
    Presentation's date: 2011-03
    Presentation of work at congresses

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    Simultaneous encoding of information in the optical phase and amplitude for upstream transmission is demonstrated with an integrated SOA/REAM of small form factor. The crosstalk penalties between the QAM tributaries are assessed and discussed.

  • Test-bed functionality of the SARDANA hybrid NG-PON

     Prat Goma, Josep; Polo Querol, Victor Manuel; Lazaro Villa, Jose Antonio; Bonada, F.; López Pastor, Eduardo Tommy; Schrenk, Bernhard; Omella, M.; Saliou, F.; Le, Q.T.; Chanclou, P.; Leino, D.; Soila, R.; Spirou, S.; Costa, L.; Teixeira, A.; Tosi-Beleffi, G.M.; Klonidis, Dimitrios; Tomkos, Ioannis
    Advanced Photonics Congress Access Networks and In-house Communications
    Presentation's date: 2011-06-11
    Presentation of work at congresses

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    The tests with broadband multimedia services of the SARDANA multi-layer prototype prove the feasibility of scalable hybrid DWDM/TDM-PON FTTH networks with resilient optically-integrated ring-trees architecture.

  • Vehículo eléctrico radiocontrol

     Salueña Berna, Javier; Schrenk, Bernhard; Lazaro Villa, Jose Antonio; Bakopoulos, Paraskevas; Kazmierski, Christophe; Prat Goma, Josep; Llovet Vidal, Aleix
    Date of request: 2011-02-22
    Invention patent

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    Vehículo eléctrico radiocontrol, con chasis (1), ruedas delanteras (2) guiadas por la dirección (3) y accionadas mediante un servomotor (4) y antena receptora (5), y un motor eléctrico (6) que acciona las ruedas traseras (7), y una pila de combustible (8), que comprende un depósito (9) de seguridad con una disolución de un hidróxido de cualquier metal alcalino o alcalinotérreo en agua y residuos de aluminio que produce hidrógeno, y un dispositivo de purificación (10) conectado al depósito (9) a través de un tubo (11), y a la pila de combustible (8) a través de otro tubo (12), de modo que el hidrógeno que circula a través del tubo (11), entrando en el dispositivo de purificación (10) que lo purifica, y saliendo a través del tubo (12) hacia la pila de combustible (8) que lo transforma en electricidad que se utiliza para accionar el motor (6) y el servomotor (4). El vehículo puede actuar también de forma híbrida.

  • MÉTODO Y APARATO PARA ENLACE ÓPTICO BIDIRECCIONAL CON MODULACIÓN SIMULTÁNEA DE AMPLITUD Y FASE MEDIANTE UN DISPOSITIVO DE SEMICONDUCTOR INTEGRADO Y AGNÓSTICO A LA LONGITUD DE ONDA

     Schrenk, Bernhard; Lazaro Villa, Jose Antonio; Bakopoulos, Paraskevas; Kazmierski, Christophe; Prat Goma, Josep
    Date of request: 2011-03-04
    Invention patent

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    Método y aparato para enlace óptico bidireccional con modulación simultánea de amplitud y fase mediante un dispositivo de semiconductor integrado y agnóstico a la longitud de onda.

    La presente invención se refiere a un método y aparato óptico para un enlace óptico bidireccional que utiliza un dispositivo semiconductor simple, integrado y agnóstico a la longitud de onda para lograr la transmisión señales mediante la modulación simultánea de la luz en fase y en amplitud.

  • On an ONU for full-duplex 10.5 Gbps/lambda with shared delay interferometer for format conversion and chirp filtering

     Schrenk, Bernhard; Stamatiadis, C.; Lazarou, I.; Maziotis, Alexandros; de Valicourt, Guilhem; Lazaro Villa, Jose Antonio; Prat Goma, Josep; Avramopoulos, Hercules
    Optical Fiber Communication Conference and Exposition
    Presentation's date: 2011-03
    Presentation of work at congresses

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    Chirped IRZ downstream is used together with a delay interferometer and a RSOA at a low complexity ONU for full-duplex 10.5Gbps transmission on a single wavelength, supported by modulation format conversion and optical offset filtering.

  • FSK plus ASK/ASK Operation for Optical 20/10 Gbps Access Networks with Simple Reflective User Terminals

     Schrenk, Bernhard; de Valicourt, Guilhem; Lazaro Villa, Jose Antonio; Prat Goma, Josep
    Optical Fiber Communication Conference and Exposition
    Presentation's date: 2011-03
    Presentation of work at congresses

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  • Bandwidth assignment criteria against rayleigh backscattering effect in TDM-PON single-fibre wavelength-reuse networks

     López Pastor, Eduardo Tommy; Lazaro Villa, Jose Antonio; Polo Querol, Victor Manuel; Prat Goma, Josep
    International Conference on Transparent Optical Networks
    Presentation's date: 2011-06-26
    Presentation of work at congresses

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    In this paper, theoretical and numerical analysis for Rayleigh Backscattering (RB) in TDM-PON full-duplex single-fiber bidirectional transmission with burst mode upstream and reflective ONU are presented. The results show that some scenarios, based on wavelength-reuse networks, require special criteria for the bandwidth allocation to avoid excessive RB due to crosstalk between ONUs.

  • Rayleigh Scattering Tolerant PON Assisted by Four-Wave Mixing in SOA-based ONUs

     Schrenk, Bernhard; de Valicourt, Guilhem; Lazaro Villa, Jose Antonio; Brenot, Romain; Prat Goma, Josep
    Journal of lightwave technology
    Date of publication: 2010-12-01
    Journal article

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  • Dual Waveband Remote Node for Extended Reach Full-Duplex 10 Gb/s Hybrid PONs

     Schrenk, Bernhard; Chatzi, Sotiria; Bonada Bo, Francesc; Lazaro Villa, Jose Antonio; Tomkos, Ioannis; Prat Goma, Josep
    Journal of lightwave technology
    Date of publication: 2010-05-15
    Journal article

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  • Assessment and mitigation of Erbium-doped fibre amplifiers (EDFA) gain transients in hybrid wavelength division multiplexing/time division multiplexing passive optical network (WDM/TDM PON) in the presence of packet-based traffic

     Neto, B.; Reis, Catarina; Dionisio, R.P; Ferreira, J.M; Lazaro Villa, Jose Antonio; Tosi Beleffi, Giorgio; Pinto, A.N; Nogueira, R.; Teixeira, A.; Prat Goma, Josep; Andre, P. S
    IET Optoelectronics
    Date of publication: 2010-12
    Journal article

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    Colorless FSK demodulation and detection with integrated Fabry-Perot-type SOA/REAM  Open access

     Schrenk, Bernhard; Lazaro Villa, Jose Antonio; Kazmierski, Christophe; Prat Goma, Josep
    IEEE photonics technology letters
    Date of publication: 2010-06-01
    Journal article

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    A receiver for optical frequency modulated signals, based on colorless demodulation and detection, is presented. An integrated combination of semiconductor optical amplifier (SOA) and reflective electroabsorption modulator (REAM) is designed to obtain a comb-like spectral detection function, replacing the typically required costly frequency discrimination filter. The spectral properties of the designed SOA/REAM chip are discussed and the reception of a 10-Gb/s optical frequency modulated downstream signal is demonstrated, proving the applicability as receiving optical subsystem in the customer premises equipment of fiber-to-the-home access networks with wavelength reuse for upstream transmission and no downstream crosstalk.

  • Design Characteristics for a Full-Duplex IM/IM Bidirectional Transmission at 10 Gb/s Using Low Bandwidth RSOA

     Papagiannakis, Ioannis; Omella Cancer, Mireia Esther; Klonidis, Dimitrios; Lazaro Villa, Jose Antonio; Birbas, Alexios; Kikidis, John; Tomkos, Ioannis; Prat Goma, Josep
    Journal of lightwave technology
    Date of publication: 2010-04-01
    Journal article

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  • Direct 10-Gb2Fs Modulation of a Single-Section RSOA in PONs With High Optical Budget

     Schrenk, Bernhard; de Valicourt, Guilhem; Omella Cancer, Mireia Esther; Lazaro Villa, Jose Antonio; Brenot, Romain; Prat Goma, Josep
    IEEE photonics technology letters
    Date of publication: 2010-03-15
    Journal article

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  • Remotely pumped long-reach hybrid PON with wavelengthrReuse in RSOA-based ONUs

     Schrenk, Bernhard; Bonada Bo, Francesc; Lazaro Villa, Jose Antonio; Prat Goma, Josep
    Journal of lightwave technology
    Date of publication: 2010-12-20
    Journal article

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    Optimization of Rayleigh-limited WDM-PONs with reflective ONU by MUX positioning and optimal ONU gain  Open access

     López Pastor, Eduardo Tommy; Lazaro Villa, Jose Antonio; Arellano Pinilla, Cristina; Polo Querol, Victor Manuel; Prat Goma, Josep
    IEEE photonics technology letters
    Date of publication: 2010-01
    Journal article

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    In this work, the influence of the distribution element position and the reflective optical network unit (ONU) gain in wavelength-division-multiplexing passive optical networks are reported. After the theoretical and experimental analysis, it is determined that the best crosstalk-to-signal ratio is achieved if the multiplexer is placed either in the ONU or optical light termination vicinity, and the ONU gain has a new optimum value depending on the position. Also, it is demonstrated that Rayleigh backscattering is generally irrelevant in downstream transmission.

  • NEW GENERATION FTTH ONU AND OLT DESIGN FOR UPSTREAM TRANSMISSION IN WDM PON INCLUDING OPTIMIZED COMBINATION OF ELECTRONICS AND OPTICS  Open access  awarded activity

     Omella Càncer, Mireia Esther
    Defense's date: 2010-10-18
    Department of Signal Theory and Communications, Universitat Politècnica de Catalunya
    Theses

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    This research is developed in the context of the Next Generation of Passive Optical Networks (NG-PON) for Fibre to the Home (FTTH) network. In this thesis, several techniques are proposed in order to increase the network capacity, dealing with the main optical impairments present in PON with minimum infrastructure, and with the goals of wavelength transparency and cost effectiveness. The main issues in this work are the photodetection process over chromatic dispersion (CD) and ASE noise impairments, the mitigation strategies for Rayleigh Backscattering (RB) effect and the WDM-PON RSOA-based ONUs, with their limitations of bandwidth and chirp. Regarding photodetection, a novel module which performs the mathematical function SQRT has demonstrated its linearizing capability at partially compensating the square-law of the photon to electron conversion process after reception. Improvements in RoF systems in terms of harmonics level reduction and in digital transmissions with linear FFE equalizers have been achieved. Also, the complexity requirements in MLSE receivers are reduced after the SQRT module. This module has been implemented electronically, first, by using the intrinsic non-linearity of the schottky diodes, on a microstrip circuit. After that, a MMIC chip has been designed and experimentally tested. But the SQRT module is also useful for other applications as downstream cancellation in the upstream signal in bidirectional transmissions, and to reduce the amplitude differences of the different packets in burst mode receivers, relaxing the adjustment requirements for the following limiting amplifiers. The statistics of the received signals in optically amplified (ASE dominant) systems have been also studied. The optimum function, capable of recovering the Gaussian distribution after detection, has been obtained. For systems working at FEC limit, like with MLSE, the improvement over SQRT is small, validating the good performance of the SQRT module. RB effect has been mitigated by using wavelength shifting at the ONU premises. Several wavelength shifter devices have been proposed for the first time, based in 2 and 3 arms capable of translating (in several GHz) the wavelength that comes from the OLT to avoid the overlap between the upstream signal and the RB, while maintaining the signal in the same AWG channel. These devices are less complex than the recently proposed 4-arm structures and require simpler signals than the sawtooth that is necessary for a 1-arm phase modulator. Experimental validation of the WS technique for RB mitigation has been performed, first with a commercial dual arm MZM and after by using a RSOA with a low duty square signal with improvements of 5 to 7dB in tolerance to RB. The new standards that have just been approved (XG-PON, 10G-EPON) propose the upgrading of the network towards symmetrical 10G/10G operation. However, RSOA’s bandwidth and chirp still limit the performance at these bit rates. The first 10Gb/s transmission in real time and with low BER (10-9) using a RSOA as an intensity modulator has been reported by using some of the techniques presented in this thesis: duobinary transmission and detuned optical filtering plus DFE-FFE equalization. Other techniques proposed and experimentally tested are the phase adjustment with a programmable optical filter and the direct detection together with MLSE equalization.

    Aquest treball de recerca està desenvolupat en el context de la nova generació de xarxes òptiques passives (NG-PON) de fibra fins a la llar (Fibre to the Home (FTTH)). En aquesta tesi, s’han proposat diverses tècniques que permeten augmentar la capacitat de la xarxa, tractant les principals degradacions presents en les xarxes PON amb la mínima infrestuctura, amb els objectius de mínim cost i transparència front a la longitud d’ona triada per a la transmissió. Els principals temes d’aquest treball són el procés de fotodetecció després d’una transmissió amb dispersió cromàtica (CD) i soroll d’emissió espontània (ASE), les estratègies per combatre l’efecte de Rayleigh Backscattering (RB) en la trasmissió bidireccional amb la mateixa longitud d’ona i les xarxes PON basades en unitats d’usuari (ONU) que utilitzen l’ amplificador semiconductor reflexiu (RSOA) com a transmissor, amb les seves limitacions d’ample de banda i chirp. Pel que fa a la fotodetecció, un dispositiu novedós que realitza la funció matemàtica arrel quadrada (SQRT) ha demostrat la seva capacitat de linearització al compensar parcialment la funció quadrada del procés de conversió de fotó a electró després de recepció. S’ha aconsegit millorar les prestacions en xarxes de ràdio sobre fibra en termes de reducció del nivel d’harmònics i també en transmissió de senyals digitals amb equalitzadors electrònics lineals. La complexitat de l’ equalitzador de màxima verosimilitud, o MLSE, es redueix si s’utilitza el mòdul SQRT. Aquest dispositiu s’ha implementat electrònicament en un circuit microstrip amb dos diodes schottky i també en un xip MMIC . El bloc SQRT també és útil per aplicacions de cancel•lació del senyal de baixada present en el senyal de pujada en les transmissions bidireccionals i per igualar l’amplitud dels paquets en senyals que es reben a ràfegues (burst mode). L’estadística del senyal rebut en sistemes amplificats òpticament (on domina el soroll ASE) també ha estat estudiat. La funció òptima, capaç de recuperar la distribució estadistica Gaussiana després de detecció, ha estat obtinguda. Per sistemes que treballen amb un nivell de errors en el límit FEC, com el MLSE, la millora de la funció òptima és molt petita front la SQRT, demostrant el bon funcionament del mòdul SQRT. L’efecte de RB s’ha minimitzat utilitzant la tècnica de desplaçar la longitud d’ona del senyal de baixada a la ONU. S’han disenyat diversos dispositius electro-òptics capaços de realitzar aquest desplaçament, utilitzant unes configuracions novedoses basades en 2 i 3 branques. L’efecte RB és redueix evitant el sol•lapament espectral però mantenint la longitud d’ona dins el mateix canal del AWG. Aquests dispositius són més senzills que les recentment proposades estructures basades en 4 branques i requereixen senyals més simples que el dent de serra necessari per al modulador de fase d’una branca. La tècnica WS s’ha validat experimentalment usant un MZM comercial i també usant un RSOA, aconseguint-se unes millores de 5 a 7 dB en tolerància a RB. Els nous estàndards que han estat recentment aprovats (XG-PON, 10G-EPON) proposen l’evolució de la xarxa passiva cap a la transmissió simètrica a 10Gb/s. La realitat és, però, que l’ample de banda i el chirp limiten la utilització de RSOAs a aquesta velocitat. La primera transmissió a 10Gb/s en temps real amb baixa tasa d’errors (BER=10-9) usant el RSOA com a modulador d’intensitat a la ONU ha estat presentat utilitzant les tècniques explicades en aquesta tesi: modulació duobinaria i filtrat òptic desplaçat amb equalització electrònica (DFE-FFE). Altres mètodes utilitzats han estat l’adjust de la fase amb un filtre òptic programable i el MLSE.

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    Wavelength conversion towards Rayleigh backscattering tolerant PONs via four-wave mixing in SOA-based ONUs  Open access

     Schrenk, Bernhard; Lazaro Villa, Jose Antonio; Prat Goma, Josep
    Optical Fiber Communication Conference and Exposition and National Fiber Optic Engineers Conference
    Presentation's date: 2010
    Presentation of work at congresses

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    Wavelength shifting in PONs with downstream signal remodulation is presented, allowing upstream transmission over trees with 25km feeder and 1:32 split with penalties <2dB, originally Rayleigh backscattering limited. Side-mode suppression is analyzed for hybrid PONs.