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:20260810T140226Z UID:229df34e-5795-4b01-85fe-4ef28c4d4958 SEQUENCE:1 CREATED:20260624T093342Z DESCRIPTION: This thesis investigates intensity-tunable all-glass metaopti cs based on the Kerr nonlinear response of fused silica. Phase-sensitive c haracterization methods were developed\, combining modal decomposition for structured beams with ultrafast off-axis digital holography. Low-energy m easurements of structured-light metasurfaces validated the platform and me thodology for high-energy experiments. The intensity-dependent response of fused-silica nanopillars was studied using FDTD simulations\, which predi cted only a small Kerr-induced phase shift before the expected damage thre shold. Simulations with implanted gold nanoparticles predicted a five-orde rs-of-magnitude increase of the nonlinear response\, while revealing criti cal simulation limitations. This motivated a high-energy two-dimensional e xperimental phase library as a function of nanopillar size and incident in tensity. The measured response was larger than predicted and dependent on sample orientation\, indicating additional contributions beyond the nanopi llar Kerr response. Measurements showed increasing thermal contributions w ith repetition rate at high intensity. The critical rate for thermal accum ulation was predicted as 1.8 Hz\, consistent with single-shot measurements following the 2 Hz curve. Simulations of phase response with incidence an gle showed a weak dependence for small angles\, at low or high intensity. Simulated optical vortices underwent intensity-dependent radial reshaping while preserving their topological charge\, and metalenses showed focal di splacement and deformation. The experimental library was interpreted as a two-intensity phase space for designing tunable devices. Arbitrary phase t ransformations are not accessible\, although a preliminary 800 µm -diamet er metalens produced a simulated focal shift from 89 mm to 143 mm with foc al degradation. This demonstrates partial intensity-dependent focal tuning \, while identifying the main limitations of the approach. Overall\, this work establishes a path towards intensity-tunable all-glass metaoptics by combining measured nanopillar responses with nonlinear substrate propagati on. LAST-MODIFIED:20260624T093342Z LOCATION:Sala P3 (Piso 1 do Pavilhão de Matemática) do IST URL:http://df.vps.tecnico.ulisboa.pt/en/events/intensity-tunable-all-glass -kerr-meta-optics/ X-ALT-DESC;FMTTYPE=text/html:

This thesis invest igates intensity-tunable all-glass metaoptics based on the Kerr nonlinear response of fused silica. Phase-sensitive characterization methods were de veloped\, combining modal decomposition for structured beams with ultrafas t off-axis digital holography. Low-energy measurements of structured-light metasurfaces validated the platform and methodology for high-energy exper iments.

The intensity-dependent response of fused-silica nanopil lars was studied using FDTD simulations\, which predicted only a small Ker r-induced phase shift before the expected damage threshold. Simulations wi th implanted gold nanoparticles predicted a five-orders-of-magnitude incre ase of the nonlinear response\, while revealing critical simulation limita tions. This motivated a high-energy two-dimensional experimental phase lib rary as a function of nanopillar size and incident intensity. The measured response was larger than predicted and dependent on sample orientation\, indicating additional contributions beyond the nanopillar Kerr response. < br/>
Measurements showed increasing thermal contributions with repetit ion rate at high intensity. The critical rate for thermal accumulation was predicted as 1.8 Hz\, consistent with single-shot measurements following the 2 Hz curve. Simulations of phase response with incidence angle showed a weak dependence for small angles\, at low or high intensity. Simulated o ptical vortices underwent intensity-dependent radial reshaping while prese rving their topological charge\, and metalenses showed focal displacement and deformation. The experimental library was interpreted as a two-intensi ty 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.

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