Switching technologies for future guided wave optical networks: potentials and limitations of photonics and electronics
TL;DR: This article discusses generic switching functions in telecommunications networks with a view of the possible role of photonics, and discusses the implementation of the switching functions from a photonics and electronics point of view, and applies this reasoning to look at scaling and transparency of all-optical networks based on current research.
Abstract: The continued rapid progress in the deployment of fiber optics communications has led to widespread interest in employing photonics to implement switching functions, hitherto reserved for electronics. Significant research effort has been devoted to this, and different specialized concepts have been suggested and partly demonstrated, albeit not in the field. At the same time, mainstream research and development in the area of telecommunications switching is solidly based on electronics. In this article we first give a short introduction to photonic switching. We then discuss generic switching functions in telecommunications networks with a view of the possible role of photonics, and discuss the implementation of the switching functions from a photonics and electronics point of view. We then apply this reasoning to look at scaling and transparency of all-optical networks based on our current research.
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TL;DR: In this paper, the three basic logic operations (AND, NOT, and OR) and more complex logic functions (EOR, INH, NOR, XNOR, and XOR) have been reproduced already at the molecular level.
Abstract: The tremendous pace in the development of information technology is rapidly approaching a limit. Alternative materials and operating princlples for the elaboration and communication of data in electronic circults and optical networks must be identified. Organic molecules are promising candidates for the realization of future digital processors. Their attractive features are the miniaturized dimensions and the high degree of control on molecular design possible in chemical synthesis. Indeed, nanostructures with engineered properties and specific functions can be assembled relying on the power of organic synthesis. In particular, certain molecales can be designed to switch from one state to another, when addressed with chemical, electrical, or optical stimulations, and to produce a detectable signal in response to these transformations. Binary data can be enceded on the input stimulations and output signals employing logic conventions and assumptions similar to those ruting digital electronics. Thus, binary inputs can be transduced into binary outputs relying on molecular switches. Following these design principles, the three basic logic operations (AND, NOT, and OR) and more complex logic functions (EOR, INH, NOR, XNOR, and XOR) have been reproduced already at the molecular level. Presently, these simple "molecular processors" are far from any practical application. However, these encouraging results demonstrate already that chemical systems can process binary data with designed logic protocols. Further fundamental studies on the various facets of this emerging area will reveal if and how molecular switches can become the basic components of furture logic devices. After all, chemical computers are available atready. We all carry one in our head!
595 citations
Patent•
20 Dec 2002TL;DR: In this article, the authors proposed a protocol independent optical transmission medium with passive filters at each node for dropping a band associated therewith and passively forwarding other bands through the transmission medium.
Abstract: A communications network has a plurality of nodes interconnected by an optical transmission medium. The transmission medium is capable of a carrying a plurality of wavelengths organized into bands. A filter at each node for drops a band associated therewith and passively forwards other bands through the transmission medium. A device is provided at each node for adding a band to the transmission medium. Communication can be established directly between a pair of nodes in the network sharing a common band without the active intervention of any intervening node. This allows the network to be protocol independent. Also, the low losses incurred by the passive filters permit relatively long path lengths without optical amplification.
282 citations
TL;DR: This work has developed a simple strategy to gate optical signals with optical signals by using a photoactive molecular switch and demonstrated that NAND, NOR, and NOT operations can be implemented exclusively with optical inputs and optical outputs coupling from one to three switching elements.
Abstract: A gradual transition from electrical to optical networks is accompanying the rapid progress of telecommunication technology. The urge for enhanced transmission capacity and speed is dictating this trend. In fact, large volumes of data encoded on optical signals can be transported rapidly over long distances. Their propagation along specific routes across a communication network is ensured by a combination of optical fibers and optoelectronic switches. It is becoming apparent, however, that the interplay between the routing electrical stimulations and the traveling optical signals will not be able to support the terabit-per-second capacities that will be needed in the near future. Electrical inputs cannot handle the immense parallelism potentially possible with optical signals. Operating principles to control optical signals with optical signals must be developed. Molecular and supramolecular switches are promising candidates for the realization of innovative materials for information technology. Binary digits can be encoded in their chemical, electrical, or optical inputs and outputs to execute specific logic functions. We have developed a simple strategy to gate optical signals with optical signals by using a photoactive molecular switch. We have demonstrated that NAND, NOR, and NOT operations can be implemented exclusively with optical inputs and optical outputs coupling from one to three switching elements. Our remarkably simple approach to all-optical switching might lead to the development of a new generation of devices for digital processing and communication technology.
184 citations
TL;DR: It is shown that multichannel digital transmission can be implemented on an ensemble of communicating molecules relying exclusively on the interplay of optical inputs and optical outputs.
Abstract: In present telecommunication networks, information transfer relies on the interplay of optical and electrical signals. Data are communicated optically but processed electronically. Methods to maintain the propagating signals solely at the optical level must be developed to overcome the transmission capacities and speed limits imposed by the electronic components. We have demonstrated that molecular switches can be used to gate optical signals in response to optical signals. We have realized a simple optical network consisting of three light sources, one cell containing a solution of three fluorescent molecules, one cell containing a solution of a three-state molecular switch and a detector. The light emitted by the three fluorophores is absorbed by the three states of the molecular switch. Using this simple operating principle, we have shown that multichannel digital transmission can be implemented on an ensemble of communicating molecules relying exclusively on the interplay of optical inputs and optical...
151 citations
TL;DR: In this article, a simplified analysis of noise in concatenated nonlinear analog optoelectronic repeaters is conducted, and it is shown that the bit error rate (BER) accumulation can be reduced significantly compared to a linear scheme, even with a partial nonlinearity.
Abstract: A simplified analysis of noise in concatenated nonlinear analog optoelectronic repeaters is conducted. We investigate different shapes of the nonlinearity and show that the bit-error-rate (BER) accumulation can be reduced significantly compared to a linear scheme, even with a partial nonlinearity. The results are also compared with a corresponding optically amplified linear system at 10 Gb/s.
83 citations
Cites background from "Switching technologies for future g..."
..., wavelength conversion and switching) in the optical layer, combinations of optics and electronics have gained interest [1]....
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References
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TL;DR: In this paper, an approach to the realization of a broadband, flexible, multi-wavelength transport network employing an optical network layer is presented, and the transmission, switching, line, and management/supervisory subsystems and components are described.
Abstract: An approach to the realization of a broadband, flexible, multiwavelength transport network employing an optical network layer. The design methodology for a network demonstrator is presented, and the transmission, switching, line, and management/supervisory subsystems and components are described. >
304 citations
TL;DR: In this article, the first all-optical demultiplexing of TDM data at 250Gbit/s was presented. Butts et al. proposed a TDM-based TDM demULTiplexer, called a "TOAD", which is compact and requires sub-picojoule switching energy.
Abstract: The first demonstration of all-optical demultiplexing of TDM data at 250Gbit/s is reported. The demultiplexer, called a 'TOAD', is compact and requires sub-picojoule switching energy. Crosstalk measurements of pseudorandom data in adjacent, 4ps-width time slots, exhibit a BER of less than 10-9, with strong jitter immunity.
145 citations
TL;DR: In this article, a monolithic integrated 4×4 semiconductor laser amplifier gate switch arrays comprising 24 integrated laser amplifiers have been fabricated and evaluated and the net positive optical gain between fibres, high extinction ratio, and low crosstalk is reported.
Abstract: Monolithically integrated 4×4 semiconductor laser amplifier gate switch arrays comprising 24 integrated laser amplifiers have been fabricated and evaluated. Net positive optical gain between fibres, high extinction ratio, and low crosstalk are reported.
132 citations
TL;DR: The authors present a bound on the minimum number of wavelengths needed based on the connectivity requirements of the users and the number of switching states in a network using a combination of circuit switching, wavelength routing, and frequency changing.
Abstract: The authors consider optical networks using wavelength division multiplexing, where the path a signal takes is determined by the network switches, the wavelength of the signal, and the location the signal originated. Therefore, a signal is routed through a combination of circuit switching and wavelength routing (assigning it a wavelength). They present a bound on the minimum number of wavelengths needed based on the connectivity requirements of the users and the number of switching states. In addition, they present a lower bound on the number of switching states in a network using a combination of circuit switching, wavelength routing, and frequency changing. The bounds hold for all networks with switches, wavelength routing, and wavelength changing devices. Several examples are presented including a network with near optimal wavelength re-use. >
78 citations
TL;DR: In this paper, a comparison of the switch energies of electrically controlled optical absorption switches and electronic switches is performed and it is shown that in the case with quantum box based absorption switches, the switch energy of the optical switches are generally orders of magnitude larger than those of the electronic switches for very high frequencies.
Abstract: A comparison of the switch energies of electrically controlled optical absorption switches and electronic switches is performed. It is shown that in the investigated case with quantum box based absorption switches, the switch energies of the optical switches are generally orders of magnitude larger than those of the electronic switches for very high frequencies. Consequences on integration of optical devices as well as on the potential for photonic switching and processing are briefly discussed. >
2 citations