Increasing transmission efficiency with advanced signal processing

Optical CDMA is an advanced and flexible communication technology with a potential to offer very energy efficient and highly scalable networking. In addition it can also deliver increased physical layer privacy and on-demand bandwidth sharing management. We have developed, extensively investigated, and experimentally demonstrated highly scalable approach to incoherent OCDMA which can very efficiently increase the number of simultaneous users. In addition, the introduction of an advanced photonic signal processing results in an overall system power budget improvement by nearly 3dB. Error-free operation with the BER less than 10-12 was achieved. We have also shown that with demonstrated approach we can dramatically improve number of simultaneous network users (up to ten times) while keeping the related hardware count unchanged. By comparing this results to DWDM concept, this substantial increase in number of simultaneous users did not require to add any additional wavelength laser sources and was achieved by employing just three communication wavelengths

Optical CMDA in light of current IT challenges

Optical code division multiple access (OCDMA) can provide very high spectral utilization, flexible data rates while delivering simplified network control and management. Higher channel count per the number of used wavelengths (compare to WDM) makes OCDMA a technology to be considered for the use in the number of targeted applications. By examining challenges the telecom faces today, we will discuss and show how Optical CDMA can help to overcome some of these challenges, fulfil our needs and requirements

Towards faster, secure and more energy efficient optical networks

A rapid penetration of multimedia into our lives has triggered unparallel demand for high speed Internet access and secure reliable and very efficient data transport. To satisfy these demands will require new and innovative approaches. It is becoming more clear that electronics alone will not be able to offer the needed solution. Today we already benefit from advances which revolutionized data and voice communications. The implementation of optical transport layer became the backbone of today’s high performance networks. Optical fiber offers enormous transport capacity and is capable to accommodate the growing volume of voice and data traffic. Further more, the capacity of each fiber can be further augmented. Today commercially deployed Dense Wavelength Division Multiple Access (DWDMA) networks are capable of transporting tens of Gigabits of data per second over a single DWDM wavelength channel, offering tremendous aggregate data throughputs exceeding ten Terrabits/sec. This creates new communications bottleneck at the fiber endpoints where the routing and switching takes place. Today’s routers use electronics to process and route incoming optical data packets. These electronic crossbars, however, do not provide sufficient capacity to timely, efficiently, and without any delays route terabits of incoming data traffic. The switching speed of these devices is limited by the frequency response of used materials and can not any more support desired bandwidth. Given all the above, it seems unlikely that electronics will deliver the needed bandwidth to support existing fiber capacity. We need to look for alternative solutions. There is growing believe, that all-optical switching/signal processing may offer the needed solution. We will review some of the promising approaches which if successfully implemented could result in manufacturable ultra-fast optical devices. We will attempt to predict the applicability of such devices for different applications within existing and newly emerging markets

Ultrafast all-optically controlled 2×2 crossbar switch

All-optical packet switching using all-optical routing control, where both ultrafast address recognition and routing of photonic packets were all optically performed on a header with 4 picosecond bit period, was demonstrated. Packets were self-routed through a node with no need for optoelectronic conversion. Terahertz optical asymmetric demultiplexer (TOAD) was used as an optically controlled 2×2 routing switch and as an all optical routing controller. TOAD read the individual address bits in the tightly compressed packet header and set the state of the routing switch. The bit-error rate at the switching element was measured to be less than 10-9

Terabit communications – tasks, challenges, and the impact of disruptive technologies

Throughout history, effective communication has been of THE most critical importance to all civilisations, the means employed being underpinned and enabled by the greatest scientific breakthroughs of the age. Today we live in an information age and consequently there is a growing need to send vast amounts of data both securely and at the shortest time possible across the globe. However, to keep pace with this demand it is critical that the capacity of future communication networks is able to perform accordingly. However it is an open secret that to achieve this is becoming an increasingly difficult task. In this paper we explore key technological milestones and breakthroughs that have enabled to support rapidly the growing demand for data. This will be followed by a discussion of the drivers of this demand, the socio-political consequences of this development, and the technical challenges we must overcome if demand is to be met into the future. These technical challenges encompass issues of CMOS scalability, power consumption, and data centres & network switching abilities

Signal processing in high speed OTDM networks

This paper presents the design and experimental results of an optical packet-switching testbed capable of performing message routing with single wavelength TDM packet bit rates as high as 100 Gb/s

The rising role of photonics in today's data centres

In recent years there has been a rapid growth in demand for ultra high speed data transmission with end users expecting fast, high bandwidth network access. This growth has put data centres under increasing pressure to provide greater data throughput and ever increasing data rates while at the same time improving the quality of data handling in terms of reduced latency, increased scalability and improved channel speed for users. However, data networks are becoming increasingly difficult to scale to meet this growing demand using current well established CMOS technology and architectures. As a result electronic bottlenecks are becoming apparent despite improvements in data management. The inter-related issues of electronic scalability, power consumption, copper interconnect bandwidth and the limited speed of CMOS electronics will be discussed; and the tremendous potential of optical fibre based networks to provide the necessary bandwidth will be illustrated. In addition, some applications of photonics to alleviate speed, throughput and latency issues in data networks will be discussed. Finally, progress in the form of a novel and highly scalable optical interconnect will be reviewed

Recent advancements towards all-optical signal processing

Recent years have seen a rapid growth in demand for ultra high speed data transmission with end users expecting fast, high bandwidth network access. However as data rates increase, present technology based on well-established CMOS electronics is becoming increasingly difficult to scale and consequently optical data networks are struggling to satisfy current user demands. Recently a number of advanced approaches have been reported developed to overcome this bottleneck based on all optical signal processing using silicon photonics devices

Ultrafast photonic packet switching with optical control

We report the demonstration of all-optical multi-bit address recognition at 250 Gb/s using a self-routing scheme. With bit period being only 4 ps, two address bits from each packet header were used for routing. Photonic packets can be removed(dropped) by a routing switch from network traffic at their destination. The packet-switching bit-error rate was measured to be less than 10-9

Broadband wavelength conversion based on on-chip nonlinear optical loop mirror

We demonstrate broadband wavelength conversion of 10 Gb/s RZ-OOK signals using a cross phase modulation based integrated nonlinear optical loop mirror on silicon-on-insulator