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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 1:56 |
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Conference: Bucharest University Faculty of Physics 2013 Meeting
Section: Optics, Spectroscopy, Plasma and Lasers
Title:
Photoresist Microstructures created by Two-Photon Photopolymerization Technique for Laser-Matter Interactions
Authors:
Florin Jipa, Marian Zamfirescu, Razvan Dabu
Affiliation:
National Institute for Laser Plasma and Radiation Physics - INFLPR , Atomistilor 409, 077125 Magurele, Bucharest, Romania
E-mail
florin.jipa@inflpr.ro
Keywords:
photopolymerization technique, femtosecond laser
Abstract:
Infrared (IR) femtosecond laser installations with high repetition rate can be used to create 3D structures in photoresist materials. Due to the transparency in the NIR spectral band, the femtosecond laser pulses can be focused deeply in the photoresist volume. The high NIR photons density created in the focused spot induce two-photons or multi-photons absorption. Chemical reactions are initiated and structural modifications take place. Multiphotonic absorption took place in smaller volumes than laser focused spot size, only where the laser intensity overtakes the threshold of the nonlinear optical effect. For some photopolymerizable materials in UV (387 nm, second harmonic of our laser), 2D or 3D periodic structures with hundreds of nm in size can be made by two-photon photopolymerization technique (2PP).With a sub-micrometer resolution, the photoresist materials offer an alternative to conventional high power laser targets fabrication methods.In this work different photoresist materials such as SU-8, ORMOCER, were irradiated using near-infrared femtosecond laser in order to create micro-structures which can be used as high power laser targets. Using a microscope objective with 0.5 NA, capillary microstructures were created in Ormocore material through TPP method. Keeping the IR femtosecond beam focused on the substrate surface and by translating the sample, capillary structures with reduced height and thickness were obtained. The capillary height can be increased by translating the focused beam along the Z axis through the photoresist volume.The photoresist structures can be used as template for more complex geometries. Other materials like metal or ceramics can be afterward deposited on the photopolymerised structures by different techniques, such as electroplating, thermal evaporation, pulsed laser deposition. After deposition, the photoresist material is eliminated by thermal treatment. The final target will reproduce the photoresist microstructure design.
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