Synchronous subnanosecond clock and data recovery for optically switched data centres using clock phase caching

The rapid growth in the amount of data being transferred within data centres, combined with the slowdown in Moore’s Law, creates challenges for the future scalability of electronically switched data-centre networks. Optical switches could offer a future-proof alternative, and photonic integration platforms have been demonstrated with nanosecond-scale optical switching times. End-to-end switching time is, however, currently limited by the clock and data recovery time, which typically takes microseconds, removing the benefits of nanosecond optical switching. Here we show that a clock phase caching technique can provide clock and data recovery times of under 625 ps (16 symbols at 25.6 Gb s−1). Our approach uses the measurement and storage of clock phase values in a synchronized network to simplify clock and data recovery versus conventional asynchronous approaches. We demonstrate the capabilities of our technique using a real-time prototype with commercial transceivers and validate its resilience against temperature variation and clock jitter

Hybrid Optoelectronic Router for Future Optical Packet‐ Switched Networks

With the growing demand for bandwidth and the need to support new services, several challenges are awaiting future photonic networks. In particular, the performance of current network nodes dominated by electrical routers/switches is seen as a bottleneck that is accentuated by the pressing demand for reducing the network power consumption. With the concept of performing more node functions with optics/optoelectronics, optical packet switching (OPS) provides a promising solution. We have developed a hybrid optoelectronic router (HOPR) prototype that exhibits low power consumption and low latency together with high functionality. The router is enabled by key optical/optoelectronic devices and subsystem technologies that are combined with CMOS electronics in a novel architecture to leverage the strengths of both optics/optoelectronics and electronics. In this chapter, we review our recent HOPR prototype developed for realizing a new photonic intra data center (DC) network. After briefly explaining about the HOPR‐based DC network, we highlight the underlying technologies of the new prototype that enables label processing, switching, and buffering of asynchronous arbitrary‐length 100‐Gbps (25‐Gbps × 4λs) burst‐mode optical packets with enhanced power efficiency and reduced latency

Deep photonic reservoir computing recurrent network

Deep neural networks usually process information through multiple hidden layers. However, most hardware reservoir computing recurrent networks only have one hidden reservoir layer, which significantly limits the capability of solving real-world complex tasks. Here we show a deep photonic reservoir computing (PRC) architecture, which is constructed by cascading injection-locked semiconductor lasers. In particular, the connection between successive hidden layers is all optical, without any optical-electrical conversion or analog-digital conversion. The proof of concept is demonstrated on a PRC consisting of 4 hidden layers and 320 interconnected neurons. In addition, we apply the deep PRC in the real-world signal equalization of an optical fiber communication system. It is found that the deep PRC owns strong ability to compensate the nonlinearity of fibers

Self-healing network architectures for multiwavelength optical metro/access networks.

Sun Xiaofeng.Thesis (M.Phil.)--Chinese University of Hong Kong, 2006.Includes bibliographical references (leaves 61-64).Abstracts in English and Chinese.Chapter CHAPTER 1 --- INTRODUCTION --- p.1Chapter 1.1 --- Optical network evolution --- p.2Chapter 1.1.1 --- Submarine and terrestrial long-haul fibre systems --- p.2Chapter 1.1.2 --- Metropolitan networks --- p.3Chapter 1.1.3 --- Access networks --- p.4Chapter 1.2 --- Motivation of this thesis --- p.6Chapter 1.3 --- Outline of this thesis --- p.7Chapter CHAPTER 2 --- PREVIOUS SELF-HEALING NETWORK ARCHITECTURES --- p.9Chapter 2.1 --- Introduction --- p.10Chapter 2.1.1 --- Previous protection architectures for access networks --- p.10Chapter 2.1.2 --- Previous protection architectures for metro access networks --- p.13Chapter 2.3 --- Previous protection architectures for metro backbone networks --- p.15Chapter 2.3.1 --- Unidirectional path-switched rings (UPSR) --- p.15Chapter 2.3.2 --- Bidirectional line-switched rings (BLSR) --- p.16Chapter 2.3.3 --- Ring interconnection and dual homing --- p.17Chapter 2.4 --- Summary --- p.19Chapter CHAPTER 3 --- SELF-HEALING NETWORK ARCHITECTURE FOR WDM OPTICAL ACCESS NETWORKS --- p.20Chapter 3.1 --- Introduction --- p.21Chapter 3.2 --- Star-Ring Protection Architecture (SRPA) --- p.21Chapter 3.2.1 --- Motivation --- p.21Chapter 3.2.2 --- Network topology of SRPA --- p.22Chapter 3.2.3 --- Wavelength assignment of SRPA --- p.22Chapter 3.2.4 --- Structure of ONU --- p.23Chapter 3.2.5 --- Protection mechanism --- p.25Chapter 3.2.6 --- Experimental demonstration --- p.26Chapter 3.2.7 --- Power budget --- p.28Chapter 3.2.8 --- Summary --- p.28Chapter 3.3 --- Duplicated-Tree Protection Architecture (DTPA) --- p.28Chapter 3.3.1 --- Motivation --- p.28Chapter 3.3.2 --- Network topology and wavelength assignment --- p.29Chapter 3.3.3 --- Structure of OLT --- p.30Chapter 3.3.4 --- Protection mechanism --- p.31Chapter 3.3.5 --- Experimental demonstration --- p.33Chapter 1.1.1 --- Summary --- p.34Chapter 1.4 --- Summary --- p.35Chapter CHAPTER 4 --- SINGLE-FIBER SELF-HEALING WDM RING NETWORK ARCHITECTURE FOR METRO ACCESS NETWORKS --- p.36Chapter 4.1 --- Introduction --- p.37Chapter 4.2 --- Network architecture and wavelength assignment --- p.37Chapter 4.3 --- Structure of access node --- p.39Chapter 4.4 --- Structure of hub node --- p.40Chapter 4.5 --- Protection mechanism --- p.42Chapter 4.6 --- Experimental demonstration --- p.43Chapter 4.7 --- Optimization of access node --- p.47Chapter 4.8 --- Scalability --- p.48Chapter 4.9 --- Summary --- p.49Chapter CHAPTER 5 --- SELF-HEALING WDM MESH NETWORK ARCHITECTURE FOR METRO BACKBONE NETWORKS… --- p.50Chapter 5.1 --- Introduction --- p.51Chapter 5.2 --- Network architecture and node structure --- p.51Chapter 5.3 --- Protection mechanism --- p.53Chapter 5.4 --- Experimental demonstration --- p.55Chapter 5.5 --- Summary --- p.57Chapter CHAPTER 6 --- SUMMARYAND FUTURE WORKS --- p.58Chapter 6.1 --- Summary of the Thesis --- p.59Chapter 6.2 --- Future Works --- p.59LIST OF PUBLICATIONS --- p.61REFERENCES --- p.6

Optical switching for dynamic distribution of wireless-over-fiber signals in active optical networks

El continuo crecimiento de ancho de banda demandado por los usuarios finales está provocando una gran exigencia sobre las redes de acceso. Estas exigencias sobre las redes de acceso, que principalmente emplean tecnologías inalámbricas, están migrando hacia el dominio óptico con el fin de soportar estos altos requerimientos de ancho de banda. Dependiendo de los requerimientos y características de los usuarios finales, las redes de acceso óptico han evolucionado en diferentes direcciones. En entornos residenciales y urbanos los usuarios demandan conexiones fijas de alta capacidad y bajo coste. Las redes ópticas pasivas (PON) han cumplido estos requerimiento y son las tecnologías elegidas por los operadores. En los entornos empresariales, en los cuales la calidad y la seguridad son piezas clave, las redes ópticas activas han encontrado su hueco proveyendo flexibilidad, adaptabilidad, alto rendimiento y al mismo tiempo dando soporte a sistemas de control de redes. Los proveedores de equipos están ahora girando su vista hacia nuevos mercados, donde soluciones ópticas puede ser usado eficientemente. El transporte de datos de redes de móviles (o mobile backhaul en ingles) es un mercado que se ha convertido en objetivo principal, ya que el tráfico inalámbrico está creciendo exponencialmente. Nuevos dispositivos, junto a las aplicaciones de gran consumo de ancho de banda, son los principales motivos de este crecimiento. Las tecnologías de banda base puede soportar sobradamente mobile backhaul a las actuales velocidades de transmisión. Sin embargo, debido a la ubicación de nuevas licencias libres disponibles en la banda de frecuencias y el desarrollo de las tecnologías radio a través de fibra permitiendo generación, distribución y recepción óptica de señales, la migración hacia escenarios en los que se use señales inalámbricas a través de fibra son mas probables. Además, teniendo en cuenta aspectos como la seguridad y alta movilidad de los usuarios, todo parece indicar que soluciones activas son más atractivas, siempre y cuando que los consumos de energía se mantengan dentro de límites razonables. En esta tesis, se diseñó una red óptica de acceso basada en tecnologías de radio a través de fibra. El bloque principal de la red fue un conmutador óptico basado en componentes activos (amplificadores ópticos semiconductores); el resto de la red fue diseñada acorde a la distribución por canales del conmutador óptico. Utilizando este conmutador óptico, se realizó una validación experimental de la red. El experimento consistió en una implementación de un sistema de cuatro canales operando en la banda de frecuencia WiMax y empleando una modulación llamada multiplexado de división ortogonal en frecuencia (OFDM) a 625Mb/s por canal. La información fue enviada a través de 20 km de fibra óptica, y el redireccionamiento de la señal fue llevado a cabo por un conmutador de 1 entrada y 16 salidas. El resultado es una degradación imperceptible de la señal en cada canal en el mejor y en mejor escenario en términos de interferencia entre canales. Este sistema cumple con los requisitos de una red de acceso activa para señales de radio a través de una red de acceso óptica

Control Plane Hardware Design for Optical Packet Switched Data Centre Networks

Optical packet switching for intra-data centre networks is key to addressing traffic requirements. Photonic integration and wavelength division multiplexing (WDM) can overcome bandwidth limits in switching systems. A promising technology to build a nanosecond-reconfigurable photonic-integrated switch, compatible with WDM, is the semiconductor optical amplifier (SOA). SOAs are typically used as gating elements in a broadcast-and-select (B\&S) configuration, to build an optical crossbar switch. For larger-size switching, a three-stage Clos network, based on crossbar nodes, is a viable architecture. However, the design of the switch control plane, is one of the barriers to packet switching; it should run on packet timescales, which becomes increasingly challenging as line rates get higher. The scheduler, used for the allocation of switch paths, limits control clock speed. To this end, the research contribution was the design of highly parallel hardware schedulers for crossbar and Clos network switches. On a field-programmable gate array (FPGA), the minimum scheduler clock period achieved was 5.0~ns and 5.4~ns, for a 32-port crossbar and Clos switch, respectively. By using parallel path allocation modules, one per Clos node, a minimum clock period of 7.0~ns was achieved, for a 256-port switch. For scheduler application-specific integrated circuit (ASIC) synthesis, this reduces to 2.0~ns; a record result enabling scalable packet switching. Furthermore, the control plane was demonstrated experimentally. Moreover, a cycle-accurate network emulator was developed to evaluate switch performance. Results showed a switch saturation throughput at a traffic load 60\% of capacity, with sub-microsecond packet latency, for a 256-port Clos switch, outperforming state-of-the-art optical packet switches