The interconnect bottleneck, the point at which integrated circuit

Integrated circuit

An integrated circuit or monolithic integrated circuit is an electronic circuit manufactured by the patterned diffusion of trace elements into the surface of a thin substrate of semiconductor material...

s (ICs) reach their capacity, is expected sometime around 2010.

Improved performance of computer systems has been achieved, in large part, by downscaling the IC minimum feature size. This allows the basic IC building block, the transistor

Transistor

A transistor is a semiconductor device used to amplify and switch electronic signals and power. It is composed of a semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current...

, to operate at a higher frequency, performing more computations per second. However, downscaling of the minimum feature size also results in tighter packing of the wires on a microprocessor

Microprocessor

A microprocessor incorporates the functions of a computer's central processing unit on a single integrated circuit, or at most a few integrated circuits. It is a multipurpose, programmable device that accepts digital data as input, processes it according to instructions stored in its memory, and...

, which increases parasitic capacitance

Parasitic capacitance

In electrical circuits, parasitic capacitance, stray capacitance or, when relevant, self-capacitance , is an unavoidable and usually unwanted capacitance that exists between the parts of an electronic component or circuit simply because of their proximity to each other...

 and signal propagation delay. Consequently, the delay due to the communication between the parts of a chip becomes comparable to the computation delay itself. This phenomenon, known as an “interconnect bottleneck”, is becoming a major problem in high-performance computer systems.

This problem of "interconnect bottleneck" can be solved by utilizing optical interconnects to replace the long metallic interconnects. Such hybrid optical/electronic interconnects promises better performance even with larger designs. Optics has widespread use in long-distance communications; still it has not yet been widely used in chip-to-chip or on-chip interconnections because they (in centimeter or micrometer range) are not yet industry-manufacturable owing to costlier technology and lack of fully mature technologies. As optical interconnections move from computer network applications to chip level interconnections, new requirements for high connection density and alignment reliability have become as critical for the effective utilization of these links. There are still many materials, fabrication, and packaging challenges in integrating optic and electronic technologies.

See also

• Optical interconnect
  Optical interconnect
  Optical interconnect is a way of communication by optical cables. Compared to traditional cables, optical wires are capable of a much higher bandwidth, from 10 Gb/s up to 100 Gb/s....
  
  
• Parallel optical interface
  Parallel optical interface
  A parallel optical interface is a form of fiber optic technology aimed primarily at communications and networking over relatively short distances , and at high bandwidths....
  
  
• Optical communication
  Optical communication
  Optical communication is any form of telecommunication that uses light as the transmission medium.An optical communication system consists of a transmitter, which encodes a message into an optical signal, a channel, which carries the signal to its destination, and a receiver, which reproduces the...
  
  
• Optical fiber cable
  Optical fiber cable
  An optical fiber cable is a cable containing one or more optical fibers. The optical fiber elements are typically individually coated with plastic layers and contained in a protective tube suitable for the environment where the cable will be deployed....
  
  
• Thunderbolt (interface)
• Von Neumann architecture
  Von Neumann architecture
  The term Von Neumann architecture, aka the Von Neumann model, derives from a computer architecture proposal by the mathematician and early computer scientist John von Neumann and others, dated June 30, 1945, entitled First Draft of a Report on the EDVAC...
  
  
• Photonics
  Photonics
  The science of photonics includes the generation, emission, transmission, modulation, signal processing, switching, amplification, detection and sensing of light. The term photonics thereby emphasizes that photons are neither particles nor waves — they are different in that they have both particle...
  
  
• Bus (computing)
• Random access memory#Memory wall