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The light spectrum beyond the visible: physics and devices of mid- and far-Infrared radiation / Recent hypes in physics & engineering: plasmonics & metamaterials, photonics crystals and graphene

Relatore Federico Valmorra (PhD student - ETH Zurich), alumnus

Si propongono due argomenti: il tema del seminario verrà in ultima istanza concordato con gli studenti iscritti.

The light spectrum beyond the visible: physics and devices of mid- and far-Infrared radiation

Optics and photonics started studying and manipulating the visible and near-infrared spectrum. These are still ongoing efforts, but in recent years technology gained interest and started to master the nearby frequencies of the mid- and far-infrared spectrum. In the seminar I'll first discuss the basics of mid- and far-infrared radiation from a physical point of view with special attention to the different materials and approaches with respect to the visible range. Then I'll present the applications in the different fields from medical/biological analysis to data communication, going from sources to detectors with special attention to the quantum cascade structures.  This are the basic for the key device at these frequencies: the Quantum Cascade Laser. In 1994 Federico Capasso, Jerome Faist and coworkers at Bell Labs demonstrated that a multi-quantum-well structure could lase interband in contrast to most lasers, nowadays reaching wavelengths much bigger than previously possible. Such devices, after 20 years are still a topic of research for several groups around the world and are also partially commercialised. I will explain in detail the beauty of its functioning together with the challenges still facing its full exploitation.




Recent hypes in physics & engineering: plasmonics & metamaterials, photonics crystals and graphene

In this seminar I would like to discuss a few topics that obtained enormous attention (and fundings) in the last decades in physics & engineering: plasmonics & metamaterials, photonics crystals, and graphene.
Plasmonics, as the name says, is the discipline studying plasmons. These are collective electron oscillations into conductors that have interesting properties for photonics circuits, above all their spatial confinement. The natural expansion of this concept are metamaterials, literally, artificial materials. By smartly designing and taking advantage of resonances in metallic structures to the electromagnetic radiation, labs could produce new ``materials" with properties new to the natural catalogue, from negative refractive index to optical cloaking. I will discuss the very basics of the field along to some milestone-results.
Photonic crystals are a sort of extension of the concept of metamaterials: they are the optical equivalent of semiconductors. With the technological advances of the past decades we can fabricate structures that we design up to the nanometric scale. These allowed to devise structures that produce bands for light, exactly in parallel to the semiconductor bands for the electrons. I will discuss the basics of the concept, how it was possible to realise it and which advances and applications offered.
Graphene is The Material of the last decade: it has been extensively studied and funded. Graphene is a monolayer of Carbon atoms arranged in a honey-comb lattice. Such structure makes it, in the right experimental conditions, the best conductor known to date for physical experiments, recognised with the Nobel prize in 2010. I will discuss the material from a physical point of view along with its advantages in specific fields like electronics, photonics, optoelectronics, as well as its disadvantages.

 

This seminar specially aims at physicists and engineers. The attendants to the seminar need as prerequisites a basic knowledge of optics, of quantum mechanics (wave functions of a quantum well) and solid state physics (semiconductor band structure).


Calendario delle lezioni

Giovedì 17 dicembre 18:00-20:00
Lunedì 21 dicembre - 16:00-18:00; 20:30-22:30
Martedì 22 dicembre - 18:00-20:00