Chris Stevens BA DPhil

Chris moved to Engineering in 1998 with a Royal Academy of Engineering Senior Research Fellowship initially working in optical heterodyne techniques and ultrafast electronics.

Since 2000 he has been a Fellow of St Hugh’s college and a Associated Professor of Engineering Science. Since the he has been heavily involved in communications Engineering and developed an interest in Metamaterials with extensive publication in UWB communications, Metamaterial physics, Applications of Manetoinductive and other slow waves. Other interests include RF tags for insects and birds (BioTracks) and Secure non-quantum communications.

Chris has founded three spinout companies from work during this time covering applications in Surveying, Medical imaging and Wireless power transfer.

In 2021 Chris took a year off with his family, bought a boat and sailed her across the Atlantic.

In his spare time, Chris spends quite a lot of time underwater.

In his early days (late 1990s) at the Engineering department Chris explored Ultrafast electronics and superconductors with the aim being to maximise the speed of conventional logic based computing devices. Clock speeds up to 1THz were explored.

Later work included development of Ultrawideband communications which eventually lead to the wimedia standard.

Chris’ current main research area is Metamaterials and their applications. These fascinating engineered materials allow us to do exciting new things with electromagnetic fields, with sound, and even with light.

Early developments from work in this area included novel pickups for MRI machines, programmable RF filters and other components.

The past 20 years has included extensive exploration of the properties of slow waves in some classes of metamaterials. This eventually lead to  the development of wireless power transfer technology. A Spinout company (Metaboards Holdings) was founded based on this and related work.

As part of the metamaterials research Chris has developed metamaterials for data and power transfer aimed at replacing printed circuit boards. Recently this has expanded with 3D circuits and their fabrication being a subject of study.

Current research activities include, Metamaterial sensors, Biomedical imaging Technqiues, Secure Communnications and Metamaterial Antennas.

Metamaterial Devices

Over the last ~15 years a gradual increase in interest in the applications of metamaterials has spawned a new research interest here in the development of Magneto-Inductive Wave Devices  for a variety of high frequency applications including NMR microscopy, Ultra High Q RF filters and Ground penetrating Radar.  In particular, Chris is very interested in the development of MIW structures as data connectors, power distribution networks and for electrical machinery.

Ultrafast Electronics

Chris' original research area is Ultrafast Electronics which is a rather catch-all term for research into the ultimate speed for electronic devices and systems. This field engages a wide range of disciplines and requires expertise in RF circuit layout, condensed matter physics, superconductivity, quantum properties of matter and materials science. In order to evaluate the performance of ultrafast electronic systems we have to develop new methods for analysing electromagnetic signals.

Much of the work in the group to date has centred on the development of new techniques with which to investigate circuit performance at >100GHz speeds where conventional circuit analysis techniques are impossible to implement. We have developed methods for current and Photokinetic Sampling,  and the ultrafast STM (funded by the Royal Society) which enables probing of nanoscale electronic components with sub picosecond time resolution. Current work includes te development of a Terahertz impedance analyser.

Communications

In addition to his work on electronics, Chris is very active in the allied area of ultrawideband (UWB) communications and electromagnetics with current projects investigating the propagation of UWB signals in a variety of environments. One significant area is the development of wireless backplane technologies for small and medium scale electronics assemblies. Typical cost for back-planes in mobile base stations for instance is often in excess of $4000. Removing the need for this component increases flexibility and reduces costs.

He has a strong interest in the imaging possibilities presented by UWB signals and systems, particularly from the high contrast nature of their interaction with living tissue which has spurred a new research area in UWB medical imaging.

Chris is also active in low frequency electromagnetics with projects in contactless power transfer and TSS- Oxford KTP Project: Submarine Electromagnetics and Ultra-wideband communications.