BEGIN:VCALENDAR VERSION:2.0 PRODID:-//linuxsoftware.nz//NONSGML Joyous v1.4//EN BEGIN:VEVENT SUMMARY:Intensity-Tunable All-Glass Kerr Meta-Optics DTSTART:20260626T110000Z DTEND:20260626T130000Z DTSTAMP:20260927T213852Z UID:229df34e-5795-4b01-85fe-4ef28c4d4958 SEQUENCE:2 CREATED:20260624T093353Z DESCRIPTION:This thesis investigates intensity-tunable all-glass metaoptic s based on the Kerr nonlinear response of fused silica. Phase-sensitive ch aracterization methods were developed\, combining modal decomposition for structured beams with ultrafast off-axis digital holography. Low-energy me asurements of structured-light metasurfaces validated the platform and met hodology for high-energy experiments. The intensity-dependent response of fused-silica nanopillars was studied using FDTD simulations\, which predic ted only a small Kerr-induced phase shift before the expected damage thres hold. Simulations with implanted gold nanoparticles predicted a five-order s-of-magnitude increase of the nonlinear response\, while revealing critic al simulation limitations. This motivated a high-energy two-dimensional ex perimental phase library as a function of nanopillar size and incident int ensity. The measured response was larger than predicted and dependent on s ample orientation\, indicating additional contributions beyond the nanopil lar Kerr response. Measurements showed increasing thermal contributions wi th repetition rate at high intensity. The critical rate for thermal accumu lation was predicted as 1.8 Hz\, consistent with single-shot measurements following the 2 Hz curve. Simulations of phase response with incidence ang le showed a weak dependence for small angles\, at low or high intensity. S imulated optical vortices underwent intensity-dependent radial reshaping w hile preserving their topological charge\, and metalenses showed focal dis placement and deformation. The experimental library was interpreted as a t wo-intensity phase space for designing tunable devices. Arbitrary phase tr ansformations are not accessible\, although a preliminary 800 µm -diamete r metalens produced a simulated focal shift from 89 mm to 143 mm with foca l degradation. This demonstrates partial intensity-dependent focal tuning\ , while identifying the main limitations of the approach. Overall\, this w ork establishes a path towards intensity-tunable all-glass metaoptics by c ombining measured nanopillar responses with nonlinear substrate propagatio n. LAST-MODIFIED:20260624T093409Z LOCATION:Sala P3 (Piso 1 do Pavilhão de Matemática) do IST URL:http://df.vps.tecnico.ulisboa.pt/pt/eventos/intensity-tunable-all-glas s-kerr-meta-optics/ X-ALT-DESC;FMTTYPE=text/html:

This thesis investi gates intensity-tunable all-glass metaoptics based on the Kerr nonlinear r esponse of fused silica. Phase-sensitive characterization methods were dev eloped\, combining modal decomposition for structured beams with ultrafast off-axis digital holography. Low-energy measurements of structured-light metasurfaces validated the platform and methodology for high-energy experi ments.

The intensity-dependent response of fused-silica nanopill ars was studied using FDTD simulations\, which predicted only a small Kerr -induced phase shift before the expected damage threshold. Simulations wit h implanted gold nanoparticles predicted a five-orders-of-magnitude increa se of the nonlinear response\, while revealing critical simulation limitat ions. This motivated a high-energy two-dimensional experimental phase libr ary as a function of nanopillar size and incident intensity. The measured response was larger than predicted and dependent on sample orientation\, i ndicating additional contributions beyond the nanopillar Kerr response.

Measurements showed increasing thermal contributions with repetiti on rate at high intensity. The critical rate for thermal accumulation was predicted as 1.8 Hz\, consistent with single-shot measurements following t he 2 Hz curve. Simulations of phase response with incidence angle showed a weak dependence for small angles\, at low or high intensity. Simulated op tical vortices underwent intensity-dependent radial reshaping while preser ving their topological charge\, and metalenses showed focal displacement a nd deformation. The experimental library was interpreted as a two-intensit y phase space for designing tunable devices.

Arbitrary phase tra nsformations are not accessible\, although a preliminary 800 µm -diameter metalens produced a simulated focal shift from 89 mm to 143 mm with focal degradation. This demonstrates partial intensity-dependent focal tuning\, while identifying the main limitations of the approach. Overall\, this wo rk establishes a path towards intensity-tunable all-glass metaoptics by co mbining measured nanopillar responses with nonlinear substrate propagation .

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