Congratulations to final year PGR Hannah Barnard, whose paper ‘Tailoring the spectral properties of layered chiral mid-infrared metamaterials‘ was published in Applied Physics Letters last month.
Hannah explains the significance of the paper’s findings:
Metamaterials, an important class of man-made material in which metals are patterned into periodic, subwavelength structures, can be designed for a number of applications. One particular application involves designing surfaces than confine electromagnetic radiation, which can then be used to probe the molecular makeup of an unknown sample, in other words, performing enhanced molecular spectroscopy. In this work we investigate one important class of metamaterial, a chiral, bi-layer structure, designed to function in the mid-IR region. We investigate the effects of adding further layers to the structure, and how this might improve its ability to enhance spectroscopy of molecules in the future. We show that adding layers tailors the spectral response (i.e. the frequency at which we can confine radiation) while maintaining the magnitude of circular dichroism (a property required to interact with chiral molecules in the future). This paper lays the foundations for future work into a functional, chiral, SEIRA (surface enhanced infrared absorption) substrate, realising enhanced spectroscopy of molecules.
You can read the full abstract of the paper below:
Abstract
The characteristics of four-layer chiral metamaterials, optically active in the important mid-infrared region, have been investigated using simulations and experiments. Results show that the spectral response of the materials can be tailored, while preserving the magnitude of the circular dichroism, relative to standard double layer metamaterials. An analysis of the coupling in these four-layer structures shows that they offer greater design freedom than might be expected from a simple consideration of double layer structures.
The authors acknowledge financial support from the Engineering and Physical Sciences Research Council (EPSRC) of the United Kingdom, via the EPSRC Center for Doctoral Training in Metamaterials (Grant No. EP/L015331/1).
The authors acknowledge useful discussions with Isaac Luxmoore, Eleanor Barr, and Huanling Zou.