Design and development of photonic devices using direct laser writing techniques

Abstract

This thesis initially presents a comprehensive exploration of laser technology and its diverse applications across various fields, from fundamental research to practical implementations. It provides a detailed examination of lasers, including their historical development and their wide-ranging applications in industries such as manufacturing, medicine, and telecommunications. The thesis explores the fundamental components of laser systems and the different types of lasers emphasizing parameters crucial for tailoring laser functionality to specific applications. Furthermore, it investigates Direct Laser Writing (DLW) techniques, providing insights into subtractive, additive, and modification processes, with a particular focus on laser ablation and femtosecond laser-induced modifications of transparent materials. Additionally, it presents the importance of controlling the focus position during the DLW techniques. Introducing the concept of integrated optics, the thesis highlights Silica and Silica-on-Silicon platforms as predominant materials for optical functions. It outlines the objectives of the "Integrated Photonic Quantum Circuits (InPhoQuC)" project aiming to advance integrated photonic quantum circuits with embedded single photon sources emphasizing the transformative shift from traditional optics to integrated photonics. Through computational simulations and experimental studies, innovative approaches are proposed to optimize the integration and increase the coupling efficiency of nanowire quantum dots (NWQDs) into photonic circuits, thus facilitating scalable quantum computing applications. Experimental investigations with a Direct Laser Writing system explore the feasibility of Silica micromachining using femtosecond laser technology and the laser writing system that has been developed in the lab. These studies are crucial for optimizing fabrication processes, particularly for integrating NWQDs and microspheres into Silica-based photonic structures. Simultaneously, the exploration of alternative techniques, such as post-process wet chemical etching, complements the understanding of femtosecond laser-based micromachining. The thesis also focuses on the development of devices created through femtosecond laser irradiation, including nanostructured Silicon substrates for enhancing biocompatibility in cancer cell adhesion studies. Additionally, the comparative studies that were conducted on the effectiveness of various lasers' in modifying the surface of intraocular lenses (IOLs) for the purpose of using them for personalized vision correction solutions further enhance the understanding of laser-material interactions. Finally, it explores the possibilities of femtosecond laser irradiation by treating PMMA and PMMA thin films doped with silver nanoparticles. Detailing the experimental setup utilizing a continuous wave Diode Laser for direct laser writing, the thesis emphasizes the importance of precise beam spot positioning and control during irradiation. For this purpose it proposes an autofocus system for controlling the diode based laser writing process. Also, presents an extensive study on customizing a diode laser module to optimize beam collimation and circularization for improved performance of the direct writing system. Continuing the exploration, the thesis details the utilization of the diode laser system for ablative decomposition of doped PMMA, with implications for the process of microfabrication used in the propulsion system of nano and pico satellites. The synthesis and characterization of PMMA thin films, doped with dye molecules such as Perylene and Coumarin, alongside the successful integration of silver nanoparticles and iron oxide nanoparticles combined with Perylene molecules for laser ablation, underscore the versatility and potential of laser-based manufacturing techniques. Lastly, the thesis investigates the synthesis and characterization of FAPbBr3 perovskite photodetectors, showcasing their self-powered operation, high sensitivity, and rapid response times under visible laser light illumination. Detailed analysis of their transient photovoltage behavior across various laser power levels and frequencies underscores their potential for efficient and cost-effective photodetection applications. This thesis contributes significantly to the advancement of laser-based technologies, offering insights into fundamental principles and practical implementations across diverse fields, from photonics and nanofabrication to photodetection and beyond.