Title of the doctoral thesis:Â Holographic Recording in Azobenzene Films: A Digital Holographic Microscopy Approach.
When: Friday 19.4.2024 at 12
Where: Tampere University, Hervanta Campus, Festia building, auditorium Pieni Sali 1 (FA032), and online.
Opponent: Professor Svetlana Santer, University of Potsdam, Germany
Custos: Professor Arri Priimägi
Abstract: This thesis explores the use of azobenzene-based materials in holographic photopatterning for the development of complex diffractive optical elements (DOEs). Capitalizing on the unique properties of azobenzene, this research demonstrates a significant advance in the manufacturing of highly precise and reconfigurable optical components, essential for thin optics and various photonic applications. The core methodology employed includes holographic recording on azobenzene films and utilizing digital holographic microscopy (DHM) for real-time monitoring of the manufacturing process. The thesis presents the development of a specialized device that combines DHM with an interference holography setup, enabling the fabrication of DOEs with precise control over their diffractive properties. This technology particularly shines in its capacity to create surface relief gratings (SRGs) with sinusoidal profiles, essential for fabricating optical Fourier surfaces. The studies follow with the multiplexing and reconfiguration of these topographies, and subsequent combination of the patterns pixel by pixel to form complex DOEs with tailored diffraction patterns. This approach offers a significant improvement over traditional photolithographic techniques, particularly in terms of process speed, non-destructive nature, and the ability to create adaptable optical elements.
The research extends to various azobenzene systems, examining their suitability for photoalignment and photopatterning that are essential for the holographic recording. The findings show a strong negative correlation between these properties, proving the need for careful materials selection depending on the application in question. A key application highlighted in this work is the manufacturing of laser cavities for thin-film organic distributed feedback lasers, demonstrating the versatility of the developed technique in producing flexible, tunable, and tailored coherent light sources. The insights gained extend to multiple fields, including augmented reality displays, soft-matter photonics, and polymer lasers, showcasing the vast potential of azobenzene holography in transforming the future of thin optical components. The thesis underscores the critical role of micro- and nanofabrication technologies in advancing the field of optics, with azobenzene-based holographic recording standing out as a promising, adaptable, and precise manufacturing technology.
The electronic thesis and more information can be found at: