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Identifier 000459790
Title Linear and nonlinear optical properties of materials for the development of 3D photonic nanostructures at telecommunication wavelengths
Alternative Title Γραμμικές και μη-γραμμικές οπτικές ιδιότητες υλικών για την ανάπτυξη τρισδιάστατων φωτονικών νανοδομών σε μήκη κύματος τηλεπικοινωνιών
Author Λαδίκα, Δήμητρα
Thesis advisor Φαρσάρη, Μαρία
Reviewer Καφεσάκη, Μαρία
Λουκάκος, Παναγιώτης
Malinauskas, Mangirdas
Παπάζογλου, Δημήτριος
Κοπιδάκης, Γεώργιος
Γλυνός, Ε.
Abstract Nanophotonics possess the ability to manipulate light on the nanoscale which plays a crucial role in the advancement of telecommunication applications. The high-speed transfer of information over long distances has driven to the development of photonic materials and structures in the nanoscale, enabling the manipulation of light, unprecedented speed and precision, surpassing the control of electrons by traditional electronics. In this context, 3D photonic crystals with sub-wavelength resolution emerged as highly promising nanostructures for applications in telecommunications. One promising technique for developing 3D photonic crystals is Multiphoton Lithography (MPL). Multiphoton Lithography (MPL) is a 3D printing technique based on the multiphoton absorption (MPA) process that offers precise control over the structural attributes including size, resolution and geometry. While many photosensitive materials have demonstrated their suitability for MPL, hybrid photoresists have become increasingly popular over the past decades due to the combination of the unique properties of organic and inorganic components, as well as the potential modification capabilities. However, there remains significant potential to further improve these materials, ultimately enabling increasing the effectiveness of MPL and tailoring the properties of 3D-printed structures for nanophotonic applications. This thesis addresses such advancements, which further involve the utilization of nonlinear optical characterization to optimize 3D nano-structuring in hybrid polymers and novel post-processing approaches to activate the resulted 3D nanostructures in the telecommunication regime. The first part of this thesis presents the nonlinear optical characterization of three new triphenylamine derivatives bearing formyl groups as efficient photoinitiators for MPL. Within this frame, the photophysical properties of the photoinitiators were studied in the context of a hybrid polymer, using three different laser systems emitting radiation at wavelengths of 515nm,780nm and 1030nm. Subsequently, the processability of these materials was evaluated through MPL, resulting in well-defined 3D structures with high-resolution features for all tested samples. Additionally, one of the PIs demonstrated a broad process window, proving its versatility for a variety of applications. Although PIs play a crucial role in achieving optimal fabrication results for an MPL material, their presence can limit the potential applications of the resulting structures due to auto-fluorescence and toxicity, among others. Therefore, the first part of this thesis also explores the investigation of the photophysical properties of the hybrid material in the absence of a PI as well as their MPL fabrication capabilities. Structures fabricated under these conditions were analyzed using photoluminescence and exhibited low auto-fluorescence characteristics. Moreover, non-photosensitized hybrid material demonstrated the processability at high resolution in 3D. These unique properties of such modified hybrid polymers open promising avenues for applications in bioengineering and micro-optics. A fundamental limitation of MPL is that the polymers in use, especially hybrid photoresists, exhibit dielectric behaviour with a glass-like refractive index. This limitation restricts the ability of MPL- produced structures to enable strong light-matter interactions in diverse spectral regions, especially in applications in the telecom band. However, in this specific spectral region, metals or doped-semiconductors, have proved to exhibit extraordinary linear and nonlinear phenomena. Metamaterials offer a way to engineer materials with precisely controlled optical properties, enabling stronger and more versatile light-matter interactions across a wide spectral range, which is particularly valuable in advanced optics and nanophotonics applications. In specific, a class of promising metamaterials is materials with permittivity (εε) near zero (ENZ) such as transparent conductive oxides (TCOs). One of the most preferable TCOs that has been studied for its ENZ behaviour is aluminum zinc oxide (AZO), as its ENZ wavelength is centered at the telecommunication wavelength. However, until now, AZO has been studied as an ENZ material in one and two dimensions. To this end, the second part of this thesis will focus on the investigation of the characteristics of AZO in three dimensions. In this way, the limitation that the MPL materials hold, will be overcome. Specifically, 3D photonic crystals will be fabricated via MPL and coated with AZO thin films via pulsed laser deposition. The combination of the AZO’s ENZ behaviour with the tailorability of the 3D photonic crystals, results in 3D photonic nanostructures responsive in the telecommunication wavelengths. This outcome strengthens the applicability of AZO as an ENZ material in three-dimensions, making it potentially suitable for applications such as PC cavities tunable in telecommunication wavelengths.
Language English
Subject 3D printing
Multiphoton absorpion
Multiphoton lithography
Nanophotonics
Photosensitive materials
Polimerization
Νανοφωτονική
Πολυμερισμός
Πολυφωτονική απορρόφηση
Πολυφωτονικός λιθογραφία
Τηλεπικοινωνίες
Τρισδιάστατη εκτύπωση
Φωτοευαίσθητα υλικά
Issue date 2023-11-29
Collection   School/Department--School of Sciences and Engineering--Department of Materials Science and Technology--Doctoral theses
  Type of Work--Doctoral theses
Permanent Link https://elocus.lib.uoc.gr//dlib/b/9/f/metadata-dlib-1698315723-212539-16218.tkl Bookmark and Share
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