2014 Faraday medal

Professor Alexander Giles Davies and Professor Edmund Linfield, University of Leeds. For their outstanding and sustained contributions to the physics and technology of the far-infrared (terahertz) frequency region of the electromagnetic spectrum.

Linfield Davies

Terahertz frequency radiation occupies a fascinating and distinctive position in the electromagnetic spectrum. Sitting between the radio and microwave regions at lower frequencies, and the infrared and visible regions at higher frequencies, it lies at the interface between electronics and optics. There are significant challenges to access and exploit this part of the spectrum, necessitating imaginative and cross-disciplinary approaches.

Professor Davies and Professor Linfield’s contributions to the science and technology of this region of the spectrum over the last two decades are remarkable not only for their outstanding and influential achievements, but also for the breadth of their activities, which have underpinned the spectacular growth of this field internationally.

Davies and Linfield’s seminal contribution was in leading the realization, and subsequent development, of the long-sought terahertz frequency quantum cascade laser, a solid-state device based on a sophisticated layered semiconductor superlattice structure. This breakthrough has opened the way for the development of the field of terahertz photonics, and engendered a number of sophisticated studies with international research groups that exploit the unique properties of this laser. These have included demonstration of a terahertz pulse amplifier exploiting the quantum cascade laser cavity, as well as the coherent optical sampling of a seeded terahertz field providing insight into the evolution of lasing and the dynamics of intersubband processes.

In parallel, Davies, Linfield and their team have made significant contributions to the development of terahertz frequency imaging and spectroscopy systems, exploiting both quantum cascade lasers as well as a number of broad bandwidth terahertz sources, and including both free-space and guided-wave geometries. Their experimental and theoretical work has underpinned fundamental understanding of the interaction of terahertz frequency radiation with matter, and in particular the complex interplay of inter-molecular and intra-molecular vibrations. This is now being exploited by researchers across a range of disciplines from biology, chemistry and medicine, through to physics, materials science, and astronomy.