Nonlinear decision-making; innovative reasoning; emergent behavior; probabilistic reasoning; adversarial modeling; intent inferencing; user modeling; information retrieval; evolutionary computation; socio-cultural modeling; intelligent systems; artificial intelligence Rahul Sarpeshkar Analog synthetic biology; biological and bio-inspired super-computing chip design; quantum circuit design, quantum computation, and hybrid quantum-classical computation; feedback control systems; medical devices; ultra-low-power, fault tolerant, and ultra-energy-efficient systems; engineering systems that operate at the fundamental limits of physics William Scheideler 3D nanomanufacturing; low-power sensors; flexible and wearable electronics; energy harvesting; wireless devices Simon G.
Shepherd HF radar development; ionospheric plasma convection and physics; solar wind, magnetosphere, ionosphere coupling; space weather and climatology Fridon Shubitidze Numerical methods in computational electromagnetics; electromagnetic sensing methodologies; detection and discrimination of sub-surface objects; linear and non-linear inverse-scattering; induced geo-electromagnetic fields; micro strip antennas; photonic band gaps; near field optics; DNA sequencing; electrostatic discharge; magnetic nano-particles hyperthermia for cancer treatment and imaging Jason T.
Sullivan Power electronics; electromagnetic design of power electronics components; micro-fabricated magnetic components; nanocomposite magnetic materials; energy efficiency and renewable energy Stephen Taylor Information operations, distributed computing and systems, computer and network security, embedded systems, surveillance technologies B. Stuart Trembly Therapeutic heating of tissue; dielectric properties of tissue; biomedical engineering; antenna theory Vikrant Vaze Logistics and transportation; aviation; healthcare analytics; healthcare systems modeling; building energy analytics; systems optimization; game theory; data-driven and statistical modeling John X.
Zhang Miniature imaging and biosensing systems; bio-inspired nanomaterials; lab-on-chip design; advanced nanofabrication technologies; multi-scale modeling of fundamental force, flow, and energy processes in biological interactions. An essential element is the network in the sky consisting of interlinked communication satellites and sensor satellites. Extensive satellite networks are also planned for commercial mobile telephone and data service applications. The text discusses the capacity advantage of optical cross-links between the satellites of the network.
Intersatellite cross-links can be either optical or radio frequency. The shorter wavelength of optical systems allows modest telescope sizes and transmission at a high data rate. Significant weight, power, and size advantages are realized over RF systems of similar performance, especially at very high data rates. However, optical space communications is still an emerging technology, with a checkered history. Many tough technical issues are yet to be resolved, and their solutions must be demonstrated before the technology is mature enough for deployment.
Among these critical technology and system issues are transmitter and receiver technology; spatial acquisition and tracking of very narrow beams; optical-mechanical-thermal engineering of high-precision optical systems for space use; and a good understanding of system architectures and techniques for design, fabrication, integration, quality assurance, and risk mitigation.
These are mainly engineering issues. The United States has a history of major disappointments in this field. The failed attempts can be traced to unsuccessful technology development, poor understanding of system. The know-how needed to successfully deploy optical communications in space does exist in U. Specifically, U.
Most U. As technology advances, optical cross-links look more attractive, but detailed analyses of costs, benefits, and risks require the development of actual space-qualified optical communications payloads that are competitive with RF cross-links.
As the Federal Communications Commission encourages the construction of global satellite networks, the requirement for several cross-link terminals per satellite, which is difficult for large RF antennae, is expected to become a strong motivation for optical cross-links.
So far, however, neither industry nor government has made the financial commitment necessary to fund such an effort in the United States. As a result, if the market develops, the United States is likely to enter it late. European and Japanese companies are not as reluctant as U.
The commercial low-Earth-orbit satellite constellations for mobile phone and small-terminal data services will be a lucrative outlet for such technology. Of the four major application areas discussed in this chapter-optical transmission, storage, display, and processing of information-the first three have succeeded in large commercial markets.
In these applications, light performs functions that cannot be done by electronics. By contrast, for most applications in information processing, electronic technology is excellent and sets a high standard of performance. In this report, the definition of optical information processing is taken to include the use of optics in data links, telecommunications switching, both analog and digital computing, and image processing. In essentially all of these applications, silicon-based electronics is presently the technology of choice.
However, as cheaper and more practical optical and optoelectronic devices become available that can be used in suitable systems, optics will play an increasingly important role. This section describes optical information processing technologies from the most advanced to the most speculative. Optical fibers are an excellent transmission medium and, as seen in the first section of this chapter, they reign undisputed in long-distance transmission links. At short distances, in local area networks LANs that link computer workstations around a campus or from desk to desk within a building, the opportunities for optics are growing rapidly, as costs come down and bandwidth needs continue to grow.
Optical data links will be important, however, only as they become sufficiently inexpensive to compete with electronics, particularly in low-end applications such as connecting desktop computers. Optical data links also require extraordinary reliability, since they transmit computer data and images. In many datacom applications, the cost per channel is reduced by using a high degree of parallelism, that is, by using arrays of lasers and detectors, connected by fiber ribbons see Figure 1.
Parallel optical links not only lower costs, but also reduce cable congestion, board area, and bandwidth demands on sources, detectors,. Motorola's optical data link package contains a fiber ribbon up to m long, driven by arrays of lasers and detectors.
Core Graduate Courses
The lasers are short-wavelength vertical cavity surface emitting, connected to an optical interface unit, which is a molded waveguide with direct chip attached to the optoelectronic array and to the fiber ribbon. Other parallel optical data links have been developed by HewlettPackard and Hitachi, among others. Courtesy of R. Nelson, Motorola. They also allow many alignments in one assembly operation and eliminate the high cost of electronic multiplexing. The result is a lower packaging cost per channel and the elimination of delays caused by electronic signal processing. In computer applications, data links are present in the local area network that connects workstations within the computing cluster, as well as to and from file servers, data communication adapters telecom and satellite , display and printer adapters, and data storage systems.
Optical data links have shown modest market penetration, with copper wiring usually being cheaper at present. Success in penetrating the market will require leverage of the enabling optical technologies. The technology driver is primarily cost; obstacles to progress include the costs of connectors and cables, packaging, and installation and alignment. Improved molding or plastic packaging as well as modeling and simulation tools for high-frequency, low-cost packages are needed.
The United States is in a strong position to capitalize on these markets. University research can help by working on advanced devices and low-cost fiber technologies. The United States is competitive in high-performance datacom, but cost reductions are needed. In low-performance datacom, the United States is strong.
OIDA has produced a detailed roadmap that lays out those technologies that will be inserted in the marketplace for specific applications.
High-bandwidth optical telecommunication systems are digital and transmit many simultaneous telephone calls or data channels with their digits interleaved in a process called multiplexing. Commercial telecommunication systems currently do all their routing electronically. At switching nodes, receivers convert optical signals from the fibers into electrical signals, which are switched and routed to the appropriate output fiber so that each phone call gets where it is intended. In an all-optical network, light signals would remain light signals throughout, and the switching would be optical.
The architecture of the system determines the approach and specifies both the hardware and the software used for multiplexing and switching. The key technological task is to identify the capabilities of optics that enable it to play crucial roles in the assembly, management, and distribution of large numbers of signals that do not all start and end at the same two distinct points. With the reduction in the cost of information transmission, switching is becoming an ever larger fraction of communications costs see Figure 1. Switching is therefore both a large challenge and a large market; today, just one fiber can saturate the switching capability of the largest switch ever made.
Since transmission cost is falling exponentially, the primary system cost will be in switching and networking, unless network architectures change to use longer spans of fiber between switches. The current practice is electronic switching, in which a transceiver detects optical signals and electronic logic sends them where they. Electronic switches use logic functions to route the signal spatially from one channel to another. This is in contrast to switches that physically change the routing, such as the patch cords used by the first telephone operators.
Partha P. Banerjee's Documents
The WDM systems see Box 1. They take advantage of the fact that the transmitted information is in the form of light, physically routing it via optical cross-connects.
- Categories, types and structures!
- Search form.
- Course Offerings;
- Electrical and Computer Engineering (EECE) < Northeastern University?
- ECE Courses?
- 7 Weeks to 10 Pounds of Muscle: The Complete Day-by-Day Program to Pack on Lean, Healthy Muscle Mass.
This keeps signals optical throughout switching and routing, and it avoids expensive optical-electronic conversions. In essence, it provides ''transparent pipes" that enable transmission of any bit rate, any packet length, any transport format, and any modulation format including SONET Synchronous Optical Network and ATM asynchronous transfer mode.
Another approach is to replace only selected electronic components with optical ones, where the optical components have a distinct advantage. For example, taking advantage of the interconnection ability of optics can enable very high-capacity switching machines, such as might be needed for terabit-per-second ATM switches.
Such devices have commonality with the advanced optical technologies developed for image processing see below. Their use of optics solves most of the physical problems inherent in high-density electrical interconnections: Optics has no frequency-dependent loss or cross talk and is intrinsically a very high-bandwidth medium; there is no distance-dependent loss or degradation; and photons allow for electrical isolation and immunity to electromagnetic interference. Meanwhile, the logic in such systems remains electronic, where it is most efficient.
Switching technology has not kept pace; the information sent on one fiber is more than enough to saturate the largest telecommunications switch in existence. Switching cost is likely to be an increasing fraction of the cost of telecommunications.
Electrical and Computer Engineering (EECE) < Northeastern University
This shows up in telephone calls costing the same whether the destination is in the same state or across the country. White, Bellcore. Multiplexing, or placing many simultaneous calls on a single line, may occur by dividing up the signals in time, space, or wavelength. When signals are multiplexed, they can travel either through fixed circuits or in separately addressed packets.
The system architecture determines when and how much the signals in different channels are multiplexed.