BEGIN:VCALENDAR VERSION:2.0 PRODID:Icfo X-PUBLISHED-TTL:P1W BEGIN:VEVENT UID:69d4b02037bbd DTSTART:20241219T110000Z SEQUENCE:0 TRANSP:OPAQUE LOCATION:Elements Room SUMMARY:ICFO | LORENZO ORSINI CLASS:PUBLIC DESCRIPTION:Topological Nanophotonics is an emerging interdisciplinary fiel d that offers a groundbreaking approach to control and manipulate light at the nanoscale. It combines principles from Topology\, Photonics\, and Nan otechnology to investigate the captivating behavior of light when confined to structures on the nanometer scale. A main goal of the community is to achieve topological edge states deeply confined below the diffraction limi t. Despite promising theoretical and experimental progress\, achieving the se edge states in a Nanophotonic system remained elusive until now.\nThis thesis is devoted to achieving these Topological edge states in a Nanophot onic system by combining several methods. First\, we used natural hyperbol ic materials to take advantage of their high-quality sub-diffraction-limit electromagnetic modes\, known as hyperbolic phonon polaritons. Additional ly\, we employed an indirect patterning technique to fabricate nanophotoni c devices\, solving fabrication-induced issues and allowing for the precis e control over the nanostructures. Finally\, we characterized these Nanoph otonic systems using scattering-type scanning near-field optical microscop y. Achieving deep subwavelength topological edge states required several f oundational achievements:\nQuantitative Polaritonic Near-Field Analysis:\n Scattering-type scanning near-field optical microscopy is a powerful imagi ng technique for studying materials beyond the diffraction limit. However\ , interpreting near-field measurements poses challenges in mapping the res ponse of polaritonic structures to meaningful physical properties. To addr ess this\, we developed a theory using the transfer matrix method to simul ate the near-field response of 1D polaritonic structures. This efficient a nd accurate analytical theory maps the near-field response to well-defined physical properties\, enhancing the understanding of near-field images an d complex polaritonic phenomena.\nAdvancing the Hyperbolic Platform:\nThe physics underlying our hyperbolic platform was largely unexplored\, leadin g to a significant gap in understanding the fundamental properties and con trol methods of indirect patterned hyperbolic materials. Our studies provi ded new insights into the behavior of hyperbolic phonon polaritons in indi rect patterned systems. We achieved three key results: first\, we gained n ew insights into the fundamental behavior of hyperbolic phonon polaritons providing a deeper understanding of their interactions within indirect pat terned systems\; second\, we investigated indirect patterned hyperbolic na nocavities achieving record-breaking quality factors\, approximately 80\, while maintaining the mode volume five orders of magnitude smaller than th e free-space excitation wavelength\; and third\, discovering that the coup ling mechanism between cavities is radiative\, significantly impacting the design of lattices and photonic crystals using indirect patterning.\nAchi eving Deep Subwavelength Topological Edge States:\nWe experimentally demon strated deep subwavelength topological edge states by implementing a one-d imensional lattice based on the Su-Schrieffer-Heeger model. The topologica l edge state was confined in a sub-diffraction volume of 0.021&mu\;m³\ ;\, four orders of magnitude smaller than the free-space excitation wavele ngth volume used to probe the system\, while maintaining a resonance quali ty factor above 100.\n \;\nThursday December 19\, 12:00 h. ICFO Elemen ts \nThesis Director: Prof. Dr. Frank Koppens DTSTAMP:20260407T072000Z END:VEVENT END:VCALENDAR