Kuppadakkath, AthiraBarreda, AngelaYang, MuyiBashiri, AyeshehHan, Seung HeonBucher, TobiasSzeghalmi, AdrianaTurchanin, AndreyGeorge, AntonyPertsch, ThomasChoi, DukStaude, IsabelleEilenberger, Falk2025-05-232025-05-2397815106705250277-786XORCID:/0000-0002-5339-3085/work/183659751http://www.scopus.com/inward/record.url?scp=85212203763&partnerID=8YFLogxKhttps://hdl.handle.net/1885/733750832Bound states in the continuum (BICs) are a category of localized states that exist within the continuum of radiating modes. The high Q-factor exhibited by these states makes quasi-BICs interesting for enhancing the emission from quantum emitters. Quasi-BICs have been experimentally realized in silicon for applications in the infrared wavelength range. Instead of silicon, hydrogenated amorphous silicon (a-Si:H) has been used for achieving quasi-BIC resonance in parts of visible spectra. Titanium dioxide (TiO2) has emerged as an alternate material for fabricating dielectric metasurfaces with high Q-factor in the visible spectral range due to its lower absorptive losses and high refractive index. However, the fabrication process for TiO2 nanostructures presents challenges compared to the well-established fabrication processes in silicon. Our work focuses on the design and fabrication of TiO2 metasurfaces supporting a quasi-BIC mode around 795 nm, with a theoretical Q-factor of 353. Experimental results reveal a maximum Q-factor of 258 at 791 nm. We discuss encountered fabrication constraints and explore possibilities for improvement in both design and fabrication processes. This study contributes to the understanding of quasi-BIC resonance in TiO2 metasurfaces, and opens avenues for further exploration in the utilization of TiO2 for high-Q dielectric metasurfaces, offering i nsights i nto t he d esign and optimization of these structures.This work was partly performed at the ACT node of the Australian National Fabrication Facility (ANFF-ACT). The authors thank the financial support of the German Research Foundation (DFG) under the frameworks of the International Research Training Group (IRTG - 2675 META-ACTIVE) and Collaborative Research Center (CRC 1375/SFB 1375 NOA), the Open Access Publication Fund of the Th\u00FCringer Universit\u00E4ts - und Landesbibliothek Jena, the European Union by project METAFAST-899673-FETOPEN-H2020, the European Social Funds, the Federal State of Thuringia, and the Federal Ministry of Education and Science of Germany. A.B. gratefully acknowledges MICINN for the Ramon y Cajal Fellowship (Grant No. RYC2021-030880-I), and Spanish national project No. PID2022-137857NA-I00.enPublisher Copyright: © 2024 SPIE.nanofabricationquasi-bound states in the continuumTiO metasurfacetwo-dimensional material2024-03-1310.1117/12.300313085212203763