Hybrid Photonic Metamaterials at the Multiscale
The field of optics is expanding rapidly and two important areas of research concern photonics and optical metamaterials. The former studies meso-scale phenomena, where packets of light are treated much like electrons in electronics. The latter deals with structures on the nano scale, with subwavelength dimensions that impart properties not easily seen in nature. Combining these two types of structures in a controlled way in hybrid devices could lead to unprecedented and unimagined functionalities. Multi-scale models developed with EU support of the HYPHONE (Hybrid photonic metamaterials at the multiscale) project are already aiding in the design process. Research focused on hyperbolic metamaterials, one of the most unusual and exciting new classes of electromagnetic metamaterials. The theoretical framework describes wave propagation in inhomogeneous media consisting of hybrid-scale metal-dielectric multilayers. These media simultaneously exploit photonic phenomena and exotic plasmonic waves, unique to hyperbolic metamaterials, produced by coupling of electrons with light in exotic nanoscale metal-dielectric environment. Work began with 1D plasmonic monolayers as building blocks that were combined into plasmonic multilayers and subsequently, multilayer multi-scale hyperbolic metamaterials. Scientists are currently pursuing experimental realisation of such multi-scale hyperbolic metamaterials. They could lead to capabilities for label-free biological imaging and manipulation with nanoscopic resolution, pushing the forefronts of modern biology and chemistry. Paying careful attention to maximisation of photon-electron interaction effects, 1D design principles were then extended to 2D structures based on nanoparticle lattices and microslot patterned membranes. The team discovered new photoelectric effects in nanoparticle lattices that could pave the way to novel photodetectors and solar cells as well as new methods in photocatalysis, photochemistry and photoelectrochemistry. Experimental work confirmed theoretical prediction of polarisation control properties of microslot membranes in the terahertz range. This very high frequency range is of relevance to numerous cutting-edge applications in spectroscopy, medical imaging and security. HYPHONE models and experimental results have closed the research gap between photonics and metamaterials, paving the way to novel devices for integrated optical applications. Along the way, the consortium has trained a new generation of scientists ready to push the frontiers of an emerging multidisciplinary field with the potential for important socioeconomic impact.
Keywords
Electromagnetic, metamaterials, multi-scale, hybrid, photonics, plasmonic, superresolution, photoelectricity, polarization, multilayers