Critical Technologies The Role of Chemistry and Chemical Engineering (1992) / Chapter Skim
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Information and Communications
Information and Communications
Pages 43-54
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From page 43... ...
~ ~ . : technologies that support an industry ~ that collects,: ~processes, displays, stores, retrieves, and transmits vast quantities of digital data.
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From page 44... ...
The effective propagation of light along an optical fiber is made possible by a core that has a higher refractive index than the cladding. The core is produced by doping pure glass with oxides of phosphorus, germanium, or aluminum, and the cladding consists of pure silica glass or silica doped with fluorides or boron oxide.
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From page 45... ...
Glass rods formed in this way are drawn into a thin fiber and coated with a polymer to protect the fiber surface from microscopic scratches and moisture that would seriously degrade fiber strength. Optical fibers are currently much more expensive than commodity glass because of the exquisite precision and control required for their manufacture.
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From page 46... ...
The future development of plasma-assisted processes depends heavily on basic research in chemistry and chemical engineering, both in designing the necessary chemical processes and in developing process control methods and sophisticated reactors to ensure manufacture with high yields at the lowest possible costs. The importance of chemistry and chemical engineering does not end with the formation of the lithographic image.
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From page 47... ...
The ceramic multichip module in the heart of a modern mainframe computer may be 5 inches square with more than 60 individually prepared layers that were fired together to form a final monolithic package that supports as many as 121 chips. At present, the complex process is as much an art as a science, and considerable research on materials and chemical processing techniques will be
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From page 48... ...
Optical interconnection and Optoelectronic Devices A striking trend in information processing is the increasing replacement of the current electronic devices and systems with hybrids known as optoelectronic devices or optically interconnected systems; at the extreme are photonic devices, which are purely light-based. Fiber-optic cables are finding increasing use for high-speed communication among computer processors and associated devices.
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From page 49... ...
Most likely this advance will use optoelectronic switches that may function by absorbing and reemitting light rather than just by transmitting it; this technology relies on the nonlinear optical properties of materials. Recent research indicates that good nonlinear optical properties can be obtained by incorporating certain chemical groups in organic polymers, aligning the groups in a strong external electric field, and then crosslinking the polymer to form a rigid three-dimensional structure.
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From page 50... ...
, is a remarkable device in which each picture element is driven by its own individual transistor. The liquid crystals used in these displays constitute a new generation of high-switchingspeed materials specifically synthesized for this application.
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From page 51... ...
Magnetic disk recording technology presents greater challenges than magnetic tape technology in both materials and process research: access speeds must be constantly increased to keep pace with performance improvements in processors. The traditional magnetic disk, a rigid aTuminum alloy substrate coated with a thin layer of magnetic iron oxide dispersed in an organic binder, is rapidly being replaced by thin-film disks in which the magnetic layer is a continuous covering of a metal alloy such as cobalt-chromium.
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From page 52... ...
The development of inexpensive polycarbonate polymers has provided adequate protection from the atmosphere while maintaining the required optical clarity and freedom from defects. Future designs will require more advanced polymeric materials that maintain these desirable properties but allow higher disk rotation speeds without deformation.
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From page 53... ...
Recently, scientists discovered that the STM can also be used to move individual atoms on a surface. Careful voltage control of the microscopic probe used in STM imaging permits a single atom to be picked up and subsequently deposited in a desired location.
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