Università Roma Tre

Part I – Interaction between the electromagnetic field and natural materials
Foundations of electromagnetic field theory. Macroscopic response of natural materials. Constitutive relations and material classification. Linearity. Dispersion. Locality. Stationary and homogeneous materials. Causality and Kramers- Kronig relations. Electric response of natural materials. Material polarization. Electronic, atomic/ionic, orientation, interface polarization mechanisms. Lorentz model: derivation and discussion. Drude model: derivation and discussion. Magnetic response of natural materials. Electrodynamic response of a magnetized ferrite.

Part II – Interaction between the electromagnetic field and artificial materials
Artificial electromagnetic materials. Historical perspective. Chiral materials. Microscopic response of matter. Polarizability concept. Electric polarizability of a dielectric sphere. Magnetic polarizability of a metallic loop. Electric polarizability of a metallic strip. Electric polarizability of a metallic loop. Polarizabilities of the metallic omega particle. Magneto-electric effect. Local field and interaction field. From microscopic to macroscopic response. Homogenization techniques. Maxwell-Garnett formula. Clausius-Mossotti formula. Bruggeman formula. Energy density for dispersive materials. Causality and energy conservation: frequency behavior of the constitutive parameters. Anomalous dispersion. Introduction to metamaterials. Historical overview. Metamaterials and their definitions. Original studies by Victor Veselago. Negative index of refraction. Negative-index materials and their first implementation. Metamaterial terminology. Artificial electric materials with negative permittivity. The wire medium. The parallel-plate medium. Noble metals at optical frequencies. Artificial electric materials in the visible. Epsilon-near-zero metamaterials. Natural and artificial magnetism. The split-ring resonator: concept, analysis, and design. Miniaturization of magnetic particles. The Multiple Split-Ring Resonator: concept, analysis, and design. The Spiral Resonator: concept, analysis, and design. The Labyrinth Resonator: concept, analysis, and design. Modelling of metallic particles in the visible. The kinetic inductance of electrons. The fishnet structure. Route towards negative index material in optics. Optical magnetism.

Part III – Time-varying materials
Solution of the wave equation in time-varying materials. Scattering phenomena at a temporal interface (reflected wave and transmitted wave). Double temporal interface: temporal slab. Multiple temporal interfaces (temporal multilayer). Space–time interface (space–time corner). Double space–time interface (space–time slab). Time-switched interfaces and related applications.

Part IV – Electromagnetic invisibility, imaging and sensing
Conceptually new electromagnetic devices based on the use of metamaterials: invisibility cloaks, superlenses, hyperlenses.
Cloaking. Reduction of object observability. Stealth and RAM technologies. Electromagnetic invisibility concept. Total scattering cross section. Absorption cross section. Optical theorem. Definition of an ideal invisibility cloak. Figure of merit of non-ideal cloaks. Transformation electromagnetics as a route to invisibility. Alternative approaches to cloaking. Main limitations and assessment. Scattering cancellation approach to cloaking. Volumetric cloaks for cylindrical and spherical objects: analysis and design. Cloaking objects with other shapes. Cloaking a cone. Implementation of scattering cancellation based volumetric cloaks at microwave and optical frequencies. Mantle cloaking: concept, modelling, design, and implementation. Cloaking applications: reduction and manipulation of optical forces. Reduction of the Casimir effect.
Imaging and sensing. The optical lens and the diffraction limit. Superlenses: concept, physical aspects, and design. Hyperlenses: concept, physical aspects, and design. Near-field-scanning optical microscope (NSOM). Aperture and apertureless NSOM tips. Advanced imaging with partially cloaked tips. Electromagnetic sensors. Biological sensors.

Notes provided by the lecturer.