Ultrafast Electronics

      

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 Our activity in Ultrafast electronics has grown from the ultrafast optical techniques which have been in use in physics, chemistry and more recently biology, for probing the most rapid processes that occur. Processes like the energy relaxation that controls the operation of semiconductor lasers, the speed with which ions engage in chemical reactions and so on have all been probed using very short light pulses with typical lengths of less than 100fs. Electronics has until recently been unable to mathc the speeds with which optical measurement techniques are able to observe processes but recent development have begun to open up the possibilities for much faster purely electronic systems opperating on sub picrosecond timescales.

Much of ultrafast electronics is devoted to analog electronic systems associated with mm-wave and sub-mm wave generation and detection, signal conversion and basic device physics being active research areas. This has also lead to a new technology of terahertz imaging which is now used routinely in security scanning applications.

Alongside these developments have been techniques based on ultra short optical pulses produced by modelocked lasers that provide the extremely high bandwidth signals with which to test and investigate device structures and performance. Using these lasers to generate gate pulses, and detecting EM fields via optical sampling techniques provides very high resolution time domain data on signals propagating on circuits and through devices.

Our research is based on exploiting the very high bandwidth of optical systems to further develop the tools to investigate circuits, including the development of tools to characterise ultrafast digital systems with clock speeds in excess of 40GHz. Examples of such logic schemes include superconducting RSFQ logic and semiconductor based RTD and nanogate transistor logics.
 

The continuing development of communication technologies to greater and greater bit rates has also provided impetus to develop our work in the frequency domain with several research projects completed and ongoing in the exploitation of optical heterodyne techniques for the characterisation of high speed optical communication systems and devices.

Research projects

Contact Prof. Chris Stevens