Sirvi Autor "Le, Nguyen Hoai An" järgi

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3D free-form optical lens — miniaturised fibre couplers for astrophotonics
(2025) Mu, Haoran; Smith, Daniel; Katkus, Tomas; Le, Nguyen Hoai An; Stonyte, Dominyka; Gailevičius, Darius; Kapsaskis, Dan; Del Frate, Alexander; Singh Bedi, Talwinder; Narbutis, Donatas; Anand, Vijayakumar; Astrauskyte, Darija; Grineviciute, Lina; Ng, Soon Hock; Glazebrook, Karl; Lawrence, Jon; Juodkazis, Saulius
In astronomy, multi-object spectrographs employ fibre positioning robots to couple the light from multiple astronomical sources (stars or galaxies) into multiple multi-mode fibres, which are distributed across the focal plane of the telescope. These fibres transport the celestial light to the entrance slit of a spectrograph (or bank of spectrographs) for analysis. For any multi-object system, mm-scale opto-mechanical solutions are required to couple the telescope light efficiently into the fibre. We demonstrate a unique micro()-optics solution to replace current optical fibre couplers. Specifically, we target technology on board the Keck telescope’s FOBOS - Fibre-Optic Broadband Optical Spectrograph — which operates at UV to IR spectral ranges. For spectrally broadband UV-IR band operation, we use glass and crystals: fused silica, crystalline quartz (transparency ), sapphire Al2O3 (), CaF (), and BaF (). The miniaturised -coupler is monolithic, with the entire light path contained within glass or crystal, seamlessly extending to the fibre entrance, which is laser-machined and precisely aligned with the optical axis.
Fraxicon for Optical Applications with Aperture ∼1 mm: Characterisation Study
(2023) Mu, Haoran; Smith, Daniel; Ng, Soon Hock; Anand, Vijayakumar; Le, Nguyen Hoai An; Dharmavarapu, Raghu; Khajehsaeidimahabadi, Zahra; Richardson, Rachael T.; Ruther, Patrick; Stoddart, Paul R.; Gricius, Henrikas; Baravykas, Tomas; Gailevicius, Darius; Seniutinas, Gediminas; Katkus, Tomas; Juodkazis, Saulius
Emerging applications of optical technologies are driving the development of miniaturised light sources, which in turn require the fabrication of matching micro-optical elements with sub-1 mm cross-sections and high optical quality. This is particularly challenging for spatially constrained biomedical applications where reduced dimensionality is required, such as endoscopy, optogenetics, or optical implants. Planarisation of a lens by the Fresnel lens approach was adapted for a conical lens (axicon) and was made by direct femtosecond 780 nm/100 fs laser writing in the SZ2080™ polymer with a photo-initiator. Optical characterisation of the positive and negative fraxicons is presented. Numerical modelling of fraxicon optical performance under illumination by incoherent and spatially extended light sources is compared with the ideal case of plane-wave illumination. Considering the potential for rapid replication in soft polymers and resists, this approach holds great promise for the most demanding technological applications.