Microstructures are usually fabricated on the surface of optical sheets to improve the optical characteristics. In this study, a new fabrication process with UV (ultraviolet) laser direct writing method is developed to embed microstructures inside the glass. Then the optical properties of glass such as reflection and refraction indexes can be modified. Single- and multi-layer microstructures are designed and embedded inside glasses to modify the optical characteristics. Both luminance and uniformity can be controlled with the embedded microstructures. Thus, the glass with inside pattern can be used as a light guide plate to increase optical performance. First, an optical software, FRED, is applied to design the microstructure configuration. Then, UV laser direct writing with output power: 2.5~ 2.6 W, repetition rate: 30 kHz, wave length: 355nm and pulse duration: 15ns is used to fabricate the microstructures inside the glass. The effect of pattern dimension such as the pitch, the layer gap, and the number of layer on the optical performance is discussed. Machining capacity of UV laser is ranging from micron to submicrometer; hence various dimensions of dot, line width, and layers can be easily embedded in the glass by one simple process. In addition, the embedded microstructures can be fabricated less damage and contamination. Finally, the optical performance of the glasses with various configurations is measured by using Spectra Colorometer (Photo Research PR650) and compared with the simulated results.

<p>In this research, we have studied the interaction between femtosecond laser and dielectric material, especially borosilicate glass, and its applications. Using laser direct writing (LDW), optical fiber sensors and selective metallization of glass surface were explored. For ultrafine selective metallization, supersonic spray deposition system was introduced combining to femtosecond laser direct writing.</p>

The objective of this research is to investigate the use of laser direct writing to micro-pattern low loss passive optical channel waveguide devices using a new hybrid organic/inorganic polymer. Review of literature shows previous methods of optical waveguide device patterning as well as application of other non-polymer materials. System setup and design of the waveguide components are discussed. Results show that laser direct writing of the hybrid polymer produce single mode interconnects with a loss of less 1dB/cm.

La fabrication de surfaces polymères complexes avec des chimies et des topographies contrôlées à l’échelle micro et nanométrique est en pleine expansion en raison de la large gamme d'applications. Une nouvelle méthode prometteuse consiste à utiliser la photopolymérisation radicalaire contrôlée par les nitroxydes (NMP2) qui exploite une alcoxyamine photosensible (AA).Pour démontrer le potentiel de fabrication de surfaces de polymères complexes, un film de polymère a d'abord été formé en irradiant avec une formulation contenant un mélange de monomère acrylique et l’alcoxyamine. Ensuite, le dépôt d'un second monomère acrylique sur ce film durci peut redémarrer une nouvelle réaction de photopolymérisation du fait de la présence d'alcoxyamines à la surface. Les radicaux peuvent être réactivés par exposition aux lampes UV et permettent de commencer un nouveau procédé de polymérisation. Une autre alternative est d'utiliser l’écriture directe par laser pour produire des structures en 2D ou 2.5D de polymère, en déplaçant le faisceau laser sur la surface de l'échantillon.Un soin particulier a été axé sur l'impact de paramètres photoniques et chimiques sur le processus de repolymérisation. Les mécanismes moléculaires qui régissent la repolymérisation pourraient être déduits de cette étude.Certaines applications montrent le potentiel de l'alcoxyamine pour générer des surfaces hydrophiles / hydrophobes ou fluorescentes pour des applications avancées. / The fabrication of complex polymer surfaces with controled chemistry and topography at the micro and nanoscale has drawn a huge attention during the last years due to the wide range of applications. A promising new method consists in using the nitroxide mediated photopolymerization (NMP2). this method exploits a photosensitive alkoxyamine (AA) that creates latent reactive radical species.To demonstrate the potential for fabrication of complex polymer surfaces, a polymer film was first formed by irradiating with a formulation containing a mixture of acrylic monomer and alkoxyamine. Then, depositing a second acrylic monomer over this cured film can reboot a new photopolymerization reaction due to the presence of alkoxyamines at the surface. The radicals can be reactivated by exposure to UV and start a new polymerization process. Another alternative is to use UV-laser direct writing to produce 2D or 2.5D polymer structure by displacing the laser beam at the surface of the sample.A special care was focused on investigating the impact of photonic and chemical parameters on the extend of the repolymerization process. The molecular mechanisms governing the repolymerization could be deduced from this study.Some applications are provided showing the potential of the alkoxyamine for generating hydrophilic/hydrophobic or fluorescent surfaces for advanced applications.

This research lays the foundation of a highly simplified maskless micro-fabrication technique which involves incorporation of laser direct writing technique combined with fountain pen based micro-patterning method to fabricate polymer-based Mach-Zehnder interferometer sensor arrays' prototype for chemical/biological sensing applications. The research provides methodology that focuses on maskless technology, allowing the definition and modification of geometric patterns through the programming of computer software, in contrast to the conventional mask-based photolithographic approach, in which a photomask must be produced before the device is fabricated. The finished waveguide sensors are evaluated on the basis of their performance as general interferometers. The waveguide developed using the fountain pen-based micro-patterning system is compared with the waveguide developed using the current technique of spin coating method for patterning of upper cladding of the waveguide. The resulting output power profile of the waveguides is generated to confirm their functionality as general interferometers. The results obtained are used to confirm the functionality of the simplified micro-fabrication technique for fabricating integrated optical polymer-based sensors and sensor arrays for chemical/biological sensing applications.

Parallèlement à l’impression jet d’encre et au bioplotting, l’impression d'éléments biologiques assistée par laser (Laser Assisted Bioprinting : LAB) qui utilise le transfert vers l’avant induit par laser (Laser Induced Forward Transfer : LIFT) a émergé comme une méthode alternative dans l’assemblage et la micro–structuration de biomatériaux et de cellules. Le LAB est une technique d’écriture directe qui offre la possibilité d’imprimer des motifs avec une haute résolution spatiale à partir d'une large gamme de matériaux solides ou liquides, tels que des diélectriques, des biomolécules et des cellules vivantes en solution.Dans nos travaux de recherche, nous avons considéré une approche expérimentale et numérique pour étudier les mécanismes physiques mis en jeu lors de la microimpression d’éléments biologiques assistée par laser. Dans un premier temps nous avons défini les paramètres rhéologiques des bioencres et les conditions de transfert (composition, épaisseur et viscosité de la bioencre et énergie laser). Puis nous avons mené une analyse statistique du volume des gouttelettes déposées pour quatre viscosités de bioencre, cinq épaisseurs de bioencre et cinq énergies laser. Ensuite nous avons conçu et mis en place un système d’imagerie résolue en temps pour étudier les effets de la viscosité sur la dynamique de l’éjection. Nous avons ainsi différencié trois régimes d'éjection en fonction de l'énergie laser déposée dans la couche absorbante, de la viscosité et de l'épaisseur de la bioencre. Parallèlement, un modèle numérique a été mis en place pour comprendre et prédire la dynamique de l’éjection en fonction de paramètres multiples : choix et épaisseur de la couche absorbante, épaisseur de la couche de bioencre, énergie laser déposée. Enfin, au regard de ces études, nous proposons un mécanisme d'éjection des microgouttelettes intervenant au cours du procédé de microimpression assistée par laser. / Over this decade, cell printing strategy has emerged as one of the promising approaches to organize cells in two and three dimensional engineered tissues. In parallel with ink-jet printing and bioplotting, Laser Assisted Bioprinting (LAB) using Laser-Induced Forward Transfer (LIFT) has emerged as an alternative method in the assembly and micropatterning of biomaterials and cells. LAB is a laser direct-write technique that offers the possibility of printing micropatterns with high spatial resolution from a wide range of solid or liquid materials, such as dielectrics, biomolecules and living cells in solution. In our research works, we considered an experimental and numerical approach to study the physical mechanisms involved in the biological elements microprinting laser assisted.First we defined the rheological parameters of bioinks and the transfer conditions (composition, thickness and viscosity of the bioink and laser energy). Then we led a statistical analysis of the volume of the transfer droplets for four viscosities of bioink, five thicknesses of bioink and five laser energies. Then we designed and implemented a system for time resolved imaging to study the effects of viscosity on the dynamics of the ejection. Thus we have differentiated three ejection regimes in function of the laser energy released in the absorbing layer, the visocsity and the thickness of the bioink. In parallel, a numerical model was developed to understand and predict the dynamics of the ejection parameters according to multiple choice and thickness of the absorbing layer, thickness of the layer bioencre, energy deposited. Finally, with regard to these studies, we propose a mechanism for ejecting droplets involved in the process of laser-assisted microprinting.

<p>Micro- and nanoparticles (MNP) attract much attention owing to their unique properties, structural tunability, and wide range of practical applications. To deposit these important materials on surfaces for generating functional coatings, a variety of special delivery systems and coating/printing techniques have been explored. Herein, spray coating technique is a promising candidate to advance the field of nanotechnology due to its low-cost, high-deposition rate, manufacturing flexibility, and compatibility with roll-to-roll processing. Despite great advances, direct scalable spray writing of functional materials at high-spatial resolution through fine patterning without a need of vacuum and mask equipment still remains challenging. Addressing these limitations requires the development of efficient spray deposition techniques and novel manufacturing approaches to effectively fabricate functional coatings. To this end, this dissertation employs three different spray coating methods of (1) cold spray; (2) atomization-assisted supersonic spray, and (3) dual velocity regime spray to address the aforementioned limitations. A comprehensive set of coating materials, design principles, and operational settings for each spray system are tailored for rapid, direct, and sustainable deposition of MNP on various substrates. Besides, through the two-phase flow modeling, droplets dispersion and deposition characteristics were investigated under both subsonic and supersonic flow conditions to uncover the process-structure-property relationships of the established spray systems. Moreover, novel spray-based manufacturing approaches are developed to fabricate functional coatings in various applications, including (i) functional polymer metallization, (ii) printed flexible electronics, (iii) advanced thin-film nanocoating, (iv) laser direct writing, and (v) electronic textiles.</p>