BEGIN:VCALENDAR VERSION:2.0 PRODID:Icfo X-PUBLISHED-TTL:P1W BEGIN:VEVENT UID:69d8d1cdce498 DTSTART:20221212T093000Z SEQUENCE:0 TRANSP:OPAQUE LOCATION:ICFO Auditorium and Online (Teams) SUMMARY:ICFO | ÁLVARO RODRÍGUEZ ECHARRI CLASS:PUBLIC DESCRIPTION:The fundamental science and technological applications of light -matter interactions on nanometer length scales form the field of study kn own as nanophotonics. Explorations in nanophotonics expand our understandi ng at the interface between classical and quantum physics\, while offering the means to address key societal challenges presented by the information and communication age\, particularly concerning the development of light- based technologies that perform faster and more efficiently than their ele ctronic counterparts.\nLight consists of propagating electromagnetic waves that can be guided\, diffracted\, or scattered through their interaction with matter. As a wave\, light is characterized by its wavelength in free space\, with the visible spectrum corresponding to ~400 - 800 nm\, while t he infrared and ultraviolet regimes of electromagnetic radiation emerge at wavelengths just above and below the visible range\, respectively. To con trol light on the nanoscale\, one must overcome the well-known Abbe limit of diffraction that prevents the focusing of light on length scales below the optical wavelength\, which can be circumvented by employing optical re sonances in materials. In particular\, we explore plasmons-the collective oscillations of conduction electrons in metals-as a platform to concentrat e electromagnetic energy down to nanometric volumes\, enhancing the associ ated electromagnetic fields and light-matter interactions. Noble metals su ch as gold\, silver\, and copper represent the standard choice of material in the study of subwavelength optics and plasmonics\, while recent advanc ements in nanofabrication enable customization of their plasmon resonances . In this thesis\, we theoretically explore the interaction of light (comp rising the mid-infrared\, visible\, and UV parts of the electromagnetic sp ectrum) with noble metal films engineered with atomic-scale precision.\nTh e manuscript starts with a comprehensive introduction of plasmons in metal lic films\, emphasizing the unique features that make these subwavelength optical excitations appealing for implementation in technological applicat ions. We go beyond classical electromagnetism approaches by incorporating semi-classical models to describe the optical response of matter at the at omic level\, which involves further complexity. Accordingly\, the first an d second chapters of the thesis are devoted to the introduction of classic al and quantum mechanical descriptions of plasmons in metallic films\, res pectively. Chapter 3 utilizes these pillars as a foundation to study three aspects of light-matter interactions in metallic thin films at the nanosc ale on which we concentrate: surface effects\, interaction with electron b eams\, and heterostructure architectures in which we combine ultra-thin me tallic films with two-dimensional materials such as graphene.\nOnce we hav e analyzed different aspects of the linear properties of the plasmonic res ponse\, Chapter 4 focuses on the nonlinear optical behaviour of metal film s. The first part describes the intrinsic nonlinear properties of metal fi lms\, whereas the second part explores a specific nonlinear phenomenon: tw o-photon luminescence in gold films. Following up with nonlinear propertie s but deviating from the use of metallic thin films\, we propose in Chapte r 5 a path to channel entangled photons encoded in the optical modes of a waveguide and excite them by direct external illumination\, leveraging the nonlinear properties of the waveguide and that overcomes involved optical elements commonly used in the generation of entangled photon pairs.\nOver all\, the thesis introduces a quantum mechanical model to understand the p lasmonic properties of noble metal films\, revealing the benefits of few-a tom-thick films for boosting light-matter interaction at the nanoscale. We envision that our findings contribute to broadening the fundamental limit s in nonlocal and nonlinear nanophotonics\, stimulating the generation of new plasmonic and optoelectronic applications.\n \;\nThesis Directors: Prof Dr. Javier Garcí\;a de Abajo and Asst. Prof. Dr. Joel D. Cox DTSTAMP:20260410T103245Z END:VEVENT END:VCALENDAR