Dr. Akhlesh Lakhtakia, Charles Godfrey Binder Professor in Engineering Science and Mechanics, will be presenting five seminars at the Ben-Gurion University of the Negev. The topics he will be presenting are Multiplasmonics, Nanoengineered Metamaterials: Sculptured Thin Films, Coping with and celebrating nanotechnology, Negatively Refracting Chiral Metamaterials, and Copycat technology.

Multiplasmonics

Abstract: Sensing technology based on the excitation of a surface-plasmonpolariton (SPP) wave guided by the interface of a metal and a dielectric material has become very popular. Although several techniques exist to launch an SPP wave guided by the interface of a metal and an isotropic homogeneous dielectric material, the commonest way is to use the Kretschmann configuration. Both the metal and the dielectric material in this configuration are layers of finite thickness. The metal film's thickness is about 50 nm, whereas the dielectric layer has to be much thicker. On the other side of the metal film is a dielectric coupling material (in the form of a prism), which is optically denser than the dielectric material. Quasi-monochromatic light is launched at an angle to the thickness direction in the coupling material towards the metal film. The fraction of illuminating light that is neither reflected nor transmitted is absorbed. As the angle of incidence increases from 0 deg, a sharp peak in absorbance, accompanied by minuscule reflectance and transmittance, indicates the excitation of an SPP wave. This sharp peak occurs only for p-polarized light, and only one SPP wave of a certain frequency can be excited.

The basic characteristic of the excitation of only one SPP wave does not change when the isotropic homogeneous dielectric partner of the metal film is made anisotropic. A far more interesting possibility emerges when the anisotropic dielectric partnering material is a sculptured thin film (STF) that is periodically nonhomogeneous in the thickness direction. A converging light beam with sufficient angular spread can then be used to excite more than one SPP-wave modes simultaneously. The propagation characteristics of different SPP-wave modes are different. Both theoretical and experimental results thus point to the emergence of multiplasmonics.

Nanoengineered Metamaterials: Sculptured Thin Films

Abstract: Morphology and performance are the two faces of the coin called a "nanoengineered metamaterial". Multifunctional performance expected of metamaterials can be engendered by cellular morphology that can be nanoengineered. Their optical and biological functionalities suggest that sculptured thin films (STFs) exemplify nanoengineered metamaterials.

Coping with and celebrating nanotechnology

Abstract:Nanotechnology is Janusian. While achievements in nanotechnology must be celebrated, we must learn to cope with its consequences too. The key lies in proper education of our children and grandchildren. After a review of current educational practices in secondary schools, the approach of just-in-time education shall be present. This approach integrates technosciences and humanities so that both future technoscientists and non-technoscientists develop a common understanding, possibly even a common language, to deal with the social, ethical, and political issues that arise from the development of nanotechnology and its convergence with other technoscientific developments.

Negatively Refracting Chiral Metamaterials

Abstract: Chirality extends the class of negatively refracting metamaterials by endowing a richer palette of electromagnetic properties. Chiral metamaterials can support negative refraction, which must be assessed in light of the closely related phenomenons of negative phase velocity and counterposition. Two categories of chiral metamaterials are being examined these days: (a) homogeneous and homogenizable chiral materials exemplified by isotropic chiral materials and Faraday chiral materials; and (b) structurally chiral materials exemplified by helicoidal bianisotropic materials.

Copycat Technology

Abstract: The conformal-evaporated-film-by-rotation technique was devised to fabricate inorganic replicas of surfaces of biological objects, such as the compound eyes of flies and the iridescent wings of butterflies, with high reliability and fidelity at the micro- and nano-scales. Potential applications include textured coatings for solar cells and other energy-harvesting structures, and photonic crystals.