Analysis and viability of WDM Technology in POF Access networks

En este TFG analizaremos la viabilidad de implementar un sistema WDM en redes de acceso, en concreto en una red de interior del hogar, eligiendo como medio de transmisión fibras de núcleo de plástico. Para abordarlo introduciremos el medio de transmisión así como los componentes actualmente disponibles en él eligiendo de acuerdo a los requerimientos de nuestro despliegue WDM aquellos más óptimos. El despliegue será caracterizado en términos de rendimiento, tasas alcanzables y posibles degradaciones que puedan aparecer en el conjunto. Compararemos el despliegue con otras tecnologías disponibles y respecto a la trasmisión monocanal destacando las ventajas que pueda aportar en el ámbito del hogar y planificaremos un enlace punto a punto caracterizado con los distintos planos, esquemas técnicos y equipos así como un presupuesto y pliego de condiciones que ejemplifique el desarrollo previo. Finalizaremos el trabajo con unas conclusiones y posibles líneas futuras de investigación que ayuden a impulsar la implantación de esta tecnología en el mercado.Piñera Buendía, P. (2014). Analysis and viability of WDM Technology in POF Access networks. http://hdl.handle.net/10251/46590.Archivo delegad

Fibre optic network supporting high speed transmission in the square kilometre array, South Africa

This thesis provides in-depth information on the high speed optical transport requirements for the Square Kilometre Array. The stringent data rates as well as timing and synchronization requirements are dealt with respect to the optical fibre technology. Regarding the data transport, we draw a clear comparison between a typical telecommunication access network and a telescope network. Invoking simulations and experiments on the field and laboratory test bed, we successfully implement a suitable telescope network using vertical cavity surface emitting laser (VCSEL) technology. Polarization effects on the KAT-7 telescope network, an operational prototype for the SKA is studied so as to estimate the expected effect in the MeerKAT telescope with transmission distances _ 12 km. The study further relates the obtained values to the expected impact on the distribution of the time and frequency reference in the MeerKAT array. Clock stability depends on the differential group delay (DGD) and polarization stability. On a 10:25 km link that includes the riser cable a DGD of 62:1 fs was attained. This corresponds to a polarization mode dispersion (PMD) coefficient of 19:4 fs=km1=2. This is a low PMD value considering telecommunication network. The PMD value is within the allowed budget in the telescope network. However, this may not be the case at longer baselines extending to over 1000 km as expected in SKA 2. The fibre's deployment contribution to the DGD is measured by comparing the deployed fibre to the undeployed of equal lengths. On the 10:25 km deployed single mode fibre, the maximum and mean DGDs measured were 217:7 fs and 84:8 fs respectively. The undeployed fibre of similar type and equal length, gave a maximum and minimum DGDs of 58:6 fs and 36:3 fs respectively. The deployment is seen to increase the maximum and minimum DGDs by factors of 3.7 and 2.3 respectively. This implies that fibre deployment is very critical in ensuring the birefringence is minimized. Polarization fluctuation recorded a maximum of 180o during the 15 hour real time astronomer use of the antenna. To ascertain the contribution of the riser cable, state of polarization (SOP) of the buried section of the single mode fibre in the link was established. A maximum SOP change of 14o over 15 hour monitoring was measured. From the stability realized on the buried section of the fibre, the change in polarization is contributed by the riser cable. The fluctuation in polarization can cause the phase of a clock signal to drift between the birefringent axes by an equal amount corresponding to DGD. We experimentally demonstrate how polarization stabilization can be attained using the polarization maintaining fibre. We also demonstrate the applicability of VCSEL technology in the SKA unidirectional data flow especially for shorter baselines < 100 km. The VCSEL is a low cost light source with attractive advantages such as low power consumption, high speed capabilities and wavelength tuneability. This work entails the use of traditional amplitude modulation commonly known as non-return-to-zero (NRZ) on-off keying (OOK) because of its simplicity and cost. For the MeerKAT typical distances, we show that even in a worst case scenario, the use of VCSEL on different fibres in MeerKAT distance is achievable. Using the impairment reduction approach, we successfully manage to achieve transmission distance beyond MeerKAT. Several in-line dispersion compensation mechanisms in telecommunication have been successfully employed. The work focused on the use of negative dispersion fibre to mitigate the chromatic dispersion effects in the optical fibre. The inverse dispersion fibre (IDF) is proposed for compensation in the conventional zero dispersion wavelength fibres, G.652 that are used at the third window. Similarly, the chromatic dispersion compensation of non-zero dispersion shifted fibre (NZDSF) is experimentally demonstrated using negative dispersion submarine reduced slope (SRS), G. 655 (-). With dispersion management, we demonstrate how transmissions beyond MeerKAT baselines can be achieved error free. A systematic investigation of the use of distributed Raman amplification to overcome the attenuation losses is provided. High on-off gains of up to 15 dB, 8 dB and 5 dB for bidirectional, forward and backward pumping respectively is achieved on a 25 km Raman optimized NZDSF-Reach fibre. Combined dispersion mitigation technique and low noise distributed Raman amplification, up to about 80 km transmission was achieved on a 4:25 Gbps modulated VCSEL using a single pump. Using bidirectional pumping, more than 100 km of transmission was achieved error free. The high gains enhance the VCSEL transmission distance. We further suggest a novel way of using the Raman pump to distribute the clock signal while amplifying the data signal streaming the astronomical data from the remote placed telescope receivers. In summary, the work presented in this thesis has demonstrated the potential use of VCSEL technology for data collection in the telescope array. We have studied the optical effects and mitigation so as to improve the clock and data transmission. This work is relevant and valuable in providing SKA with VCSELs, an option for extremely high network performance at reasonable costs

Comunicações avançadas com fibra óptica plástica

Nowadays, fiber to the Home/Curb/Building/Cabinet (FTTx) services that interconnect homes with a standard glass optical fiber cables to the core/access optical networks have brought the optical fiber at the doorsteps of our homes. However, the last few miles in home access network is still based on the limited bandwidth electronic component which supports by the cooper wires e.g. Cat-5, 6. The rapid growth of personal smart/mobile electronic devices with new developments such as video on demand, High Definition (HD) and three-Dimension (3D) television (TV), cloud computing, video conferences, etc. has been proposed new challenges for the next generation high bandwidth demand required for subscribers in home access network. In order to meet the more demanding expectations of the end user with new developments, it is necessary to improve the physical infrastructure of the existing in home networks in order to obtain the best ratio between quality of service and price of implementation. Plastic optical fibers (POFs) are point out as a promising transmission medium for short-range communication in compare to the “classic” single/multimode glass optical fibers and current cooper wire technology developments. The main advantages of POF are its easy to install, easy splicing and the possibility of using low cost optical transceivers, capability of being robust, and immunity to electromagnetic noise interference. However, the benefits of large-core POFs come at the expense of a less bandwidth and a higher attenuation than silica-based solution. The main objective of this doctoral dissertation is to explore the possibilities and develop low cost, short reach, high data rate POF-links for in home networks applications. This thesis investigates the use of multilevel modulation in particular, pulse amplitude modulation (PAM in combination of the receiver equalizer in order to overcome the bandwidth limitations of the graded index POFs. The possibility of the using multiple channels over a single fiber to increase the capacity of POF systems using commercially available multimode components is also analyzed in this dissertation. Moreover, a low cost Digitised radio signal over plastic fiber system is proposed and evaluated to deliver digital baseband data for wireline and wireless users in home access network. The deployment will be specified in terms of performance, maximum rates and any degradation that might appear in the network. Furthermore, the possibilities of the microstructured fibers in telecommunication application will be studied with main emphasis on their structural design. The photonic crystal fibers made of different highly nonlinear materials with different structures are optimized to achieve ultra-flat dispersion, high nonlinearity and low confinement loss over a broad range of wavelengths in the perspective of their usage in telecommunication applications.Hoje em dia, a possibilidade de a fibra óptica até casa (FTTH) para a transmissão simultânea de diferentes serviços como internet, telefone, televisão digital é uma realidade. No entanto, para satisfazer as expectativas mais exigentes do usuário final com novos desenvolvimentos, tais como vídeo sob demanda, de alta definição (HD) e tridimensional (3D) de televisão (TV), computação em nuvem, vídeo conferências, etc., é necessário melhorar a infra-estrutura física da existente em redes domésticas, a fim de obter a melhor relação entre a qualidade do serviço e preço de implementação. Fibra óptica de plástico (POF) é considerada um meio de transmissão promissor para comunicações de curto alcance, queando comparadas com a clássica fibra óptica de silica (tanto monomodo como multimodo) e com as tecnologias atuais baseadas em fio de cobre. As principais vantagens da POF encontramse na sua facilidade de instalação e conecção, possibilidade de uso de fontes e detectores de baixo custo, robustez e imunidade electromagnética. No entanto, o uso da POF de elevado diâmetro têm também desvantagens uma vez que esta oferece uma menor largura de banda e uma atenuação superior à fibra de sílica convêncional. Esta dissertação de doutoramento tem como principal objetivo explorar as possibilidades de desemvolvimento de componentes de baixo custo baseados em POF para redes de curto alcance, com alta taxa de transmisssão de dados. Esta tese investiga a utilização de vários formatos de modulação combinados com equalizador e receptor, de maneira a superar as limitações de largura de banda em sistemas de comunicação óptica de curto alcance. Em particular, a modulação em amplitude de impulso (PAM) é proposta e investigada a fim de aumentar a capacidade de tais sistemas. Além disso, a possibilidade de usar múltiplos canais, utilizando uma única fibra óptica, também conhecido por multiplexagem por divisão de comprimento de onda (WDM), será analisada neste trabalho. A viabilidade das tecnologias de redes de acesso tanto a nível individual como em sistemas WDM serão analisadas usando componentes multimodo disponíveis comercialmente. A implementação será especificada em termos de desempenho tanto a nível da taxas máximas de transmissão, bem como na degradação do sinal que possa ocorrer na rede. No capitulo 5 desta dissertação é apresentado sistema de radio através de fibra. Este tipo de sistemas permite a simplificação das estações base providenciando também uma elevada manutenção de custos. O principal objectivo deste estudo prende-se com a investigação do impacto da amostragem na preformance de digitalização de rádio através de fibra e também como a introdução de fibra óptica de plástico pode afetar o sistema. Além disso, a possibilidade da aplicação de fibras óticas microestruturadas em redes de telecomunicações serão estudadas com ênfase principal na sua concepção estrutural. As fibras de cristal fotônico feitas de diferentes materiais altamente não-lineares com diferentes estruturas serão otimizadas a fim de alcançar uma dispersão ultra-plana, elevada não linearidade e baixa perda de confinamento em uma vasta gama espectral, na perspectiva de seu uso em aplicações de telecomunicações.Programa Doutoral em Engenharia Eletrotécnic

High-capacity transmission over polymer optical fiber

Abstract-Polymer optical fiber (POF) is a promising transmission medium to provide broad-band telecommunication services within the customer&apos;s premises. POF offers several attractive features for data transmission such as broad bandwidth and low cost for in-house, access, and local-area-network (LAN) applications. This paper presents a review on optical transmission systems using POF and their enabling technologies. A summary is given of experimental data links with record capacity over record transmission distances. To conclude, we discuss trends for further development and research. Index Terms-Optical communications, optical fiber, polymer optical fiber

Polymer waveguide based optical interconnects for high-speed on-board communications

This dissertation presents a study of multimode polymer waveguide technology for use in board-level communication links for future data centres and supercomputers. The motivation for this work comes from the severe interconnection bandwidth challenges faced by the conventional electrical interconnections technology and the potential performance advantages of optical interconnections. This thesis presents the work to address the bandwidth bottleneck by developing high-bandwidth multimode polymer waveguides. The use of multimode waveguides provides relaxed alignment tolerances enabling low-cost assembly tools. Siloxane polymer materials developed by Dow Corning Corporation are chosen to form the waveguides in this work due to their favourable optical properties (optical losses as low as 0.03 dB/cm and the ability to withstand temperatures in excess of 350 °C) that allow the waveguides to be directly integrated on printed circuits boards (PCBs) using conventional manufacturing processes. Useful design rules for the use of the multimode polymer waveguides are theoretically derived while the bandwidth-length products are investigated under various launch conditions. Frequency-domain measurements and ultra-short pulse measurements are then carried out to investigate the bandwidth performance of the polymer waveguides under different launch conditions and with lateral misalignments. The instrument-limited frequency-domain measurements show that these waveguides exhibit bandwidth-length products (BLPs) of at least 35 GHz×m, while the pulse broadening measurements reveal the actual BLPs to be in excess of 70 GHz×m under a 50 μm multimode-fibre (MMF) launch and 100 GHz×m for a restricted launch across a wide range of input offsets (>±10 μm). This shows the potential for data transmission rates of 100 Gb/s and beyond over a single waveguide channel. A theoretical model is developed using the measured refractive index profile and good agreement with the above experimental results is found. The effects of graded refractive index profiles on the performance of waveguide components (bends, crossings) are also investigated, demonstrating that appropriate refractive index engineering can provide enhanced waveguide loss performance while exhibiting adequate bandwidth. Waveguide bends with excess loss below 1 dB for a radius >6 mm, crossings with loss less than 0.02 dB/crossing while exhibiting adequate link bandwidth (>47 GHz×m) can be achieved for a MMF launch. On this basis, advanced modulation formats are investigated across the board-level waveguide links for further increasing the on-board data rates. Record NRZ-based 40 Gb/s and 56 Gb/s PAM-4 based data transmission over a 1 m long multimode polymer spiral waveguide are theoretically and experimentally demonstrated

Broadband Receiver Electronic Circuits for Fiber-Optical Communication Systems

The exponential growth of internet traffic drives datacenters to constantly improve their capacity. As the copper based network infrastructure is being replaced by fiber-optical interconnects, new industrial standards for higher datarates are required. Several research and industrial organizations are aiming towards 400 Gb Ethernet and beyond, which brings new challenges to the field of high-speed broadband electronic circuit design. Replacing OOK with higher M-ary modulation formats and using higher datarates increases network capacity but at the cost of power. With datacenters rapidly becoming significant energy consumers on the global scale, the energy efficiency of the optical interconnect transceivers takes a primary role in the development of novel systems. There are several additional challenges unique in the design of a broadband shortreach fiber-optical receiver system. The sensitivity of the receiver depends on the noise performance of the PD and the electronics. The overall system noise must be optimized for the specific application, modulation scheme, PD and VCSEL characteristics. The topology of the transimpedance amplifier affects the noise and frequency response of the PD, so the system must be optimized as a whole. Most state-of-the-art receivers are built on high-end semiconductor SiGe and InP technologies. However, there are still several design decisions to be made in order to get low noise, high energy efficiency and adequate bandwidth. In order to overcome the frequency limitations of the optoelectronic components, bandwidth enhancement and channel equalization techniques are used. In this work several different blocks of a receiver system are designed and characterized. A broadband, 50 GHz bandwidth CB-based TIA and a tunable gain equalizer are designed in a 130 nm SiGe BiCMOS process. An ultra-broadband traveling wave amplifier is presented, based on a 250 nm InP DHBT technology demonstrating a 207 GHz bandwidth. Two TIA front-end topologies with 133 GHz bandwidth, a CB and a CE with shunt-shunt feedback, based on a 130 nm InP DHBT technology are designed and compared

Signaling for Optical Intensity Channels

With the growing popularity of social media services, e-commerce, and many other internet-based services, we are witnessing a rapid growth in the deployment of data centers and cloud computing platforms. As a result, the telecommunications industry has to continue providing additional network capacity to meet the increasing demand for bandwidth. The use of fiber-optic communications plays a key role in meeting this demand. Coherent optical transceivers improve spectral efficiency by allowing the use of multilevel in-phase and quadrature (I/Q) modulation formats, which encode information onto the optical carrier’s amplitude and phase. However, for short-haul optical links, using noncoherent optical transceivers, also known as intensity-modulated direct-detection (IM/DD) systems, is a more attractive low-cost approach. Since only the intensity of light can carry information, designing power- and spectrally-efficient modulation formats becomes challenging. Subcarrier modulation, a concept studied in wireless infrared communications, allows the use of I/Q modulation formats with IM/DD systems at the expense of power and spectral efficiency. This thesis addresses the problem of optimizing single-subcarrier modulation formats for noncoherent fiber and wireless optical communication systems in order to achieve a good trade-off between spectral efficiency, power efficiency, and cost/complexity. For the single-subcarrier three-dimensional signal space, denoted as raised-QAM in the literature, we propose a set of 4-, 8-, and 16-level modulation formats which are numerically optimized for average electrical, average optical, and peak power. In the absence of error-correcting codes, the optimized formats offer gains ranging from 0.6 to 3 dB compared to the best known formats. However, when error-correcting codes with performance near capacity are present, the obtained modulation formats offer gains ranging from 0.3 to 1 dB compared to previously known formats. In addition, laboratory experiments using the obtained 4- and 8-ary modulation formats were carried out. The performance improvement over the previously known formats conforms with the theoretical results. To address transceiver complexity, a two-dimensional signal space for optical IM/DD systems is proposed. The resulting modulation formats have simpler modulator and demodulator structures than the three-dimensional formats. Their spectra have in general narrower main lobes but slower roll-off, which make them a good choice for single-wavelength optical systems. The three-dimensional formats are more suitable for wavelength-division multiplexing systems, where crosstalk between adjacent channels is important