Femtosecond Laser Modification of Different Materials (FLAMAT)

Финансираща организация: Фонд „Научни изследвания“ в рамките на Национална научна програма „ПЕТЪР БЕРОН. НАУКА И ИНОВАЦИИ С ЕВРОПА – 2023“

Базова организация: Институт по физика на твърдото тяло „Акад. Георги Наджаков“ – БАН

Тип изследвания: Фундаментални

Project start: 01 February 2024
Project end: 01 February 2026
Duration: 24 months

Description

Femtosecond laser modification is a process by which permanent (irreversible) changes are induced in the surface characteristics of a given material at the micro- and nanoscale, including surface topography, crystalline structure, chemical composition, and polymerization, to improve its functionality.

Main objective

The main objective of the project is to investigate the effect of femtosecond laser–induced modification on the physicochemical properties and functionality of optical components with potential applications in the laser and optical industries. The research focuses on various optical coatings, such as ZrO₂, TiO₂, Al₂O₃, SiO₂, and others, as well as on different glasses and crystals used as substrates for thin-film deposition, including fused silica, borosilicate glass, BK7, and similar materials.

To achieve this objective, in-depth fundamental studies will be carried out to investigate the mechanisms and effects of femtosecond laser-induced surface modification, with particular emphasis on the linear and nonlinear optical properties, chemical structure, morphology, and surface topography of these materials. This includes a systematic investigation of how laser processing parameters, such as wavelength, pulse duration, repetition rate, and energy fluence, etc., affect the material modification process.

The originality and innovative character of the project are expressed through the investigation of the wavelength dependence of the modified material properties over the UV–VIS–IR spectral range, the study of the impact of femtosecond laser processing on the nonlinear optical properties of materials, and the enhancement of the functionalization of optical substrates intended for thin-film deposition.

Planned Activities

• Preparation of experimental samples through vacuum deposition of single-layer and multilayer dielectric coatings with different refractive indices (TiO₂, ZrO₂, Al₂O₃, SiO₂, etc.) on optical substrates.
• Configuration and optimization of a femtosecond laser system capable of operation in the UV–VIS–IR spectral range.
• Systematic investigation of the influence of laser parameters (wavelength, pulse duration, fluence, number of pulses, polarization) on material modification.
• Characterization of linear optical properties by spectrophotometry and ellipsometry.
• Experimental determination of nonlinear optical parameters (n₂ and β) using a modified z-scan method.
• Analysis of surface morphology and topography by optical microscopy, atomic force microscopy (AFM), and scanning electron microscopy (SEM).
• Investigation of chemical and structural organization through FTIR, Raman, and X-ray diffraction (XRD) analyses.
• Analysis and interpretation of the results in order to elucidate the mechanisms of laser-induced modification.

Expected Results

• New fundamental knowledge on the mechanisms of interaction between femtosecond laser radiation and various optical materials in the ultraviolet, visible, and infrared spectral ranges.
• Clarification of the influence of laser parameters (wavelength, pulse duration, fluence, number of pulses, repetition rate, and polarization) on the physicochemical properties of optical coatings and substrates.
• Evaluation of changes in the linear and nonlinear optical characteristics of the modified materials, including refractive index, optical absorption, and nonlinear optical parameters.
• Analysis of structural, morphological, and chemical modifications induced by femtosecond laser processing through a multi-analytical approach.
• Accumulation of systematized experimental data necessary for the optimization of laser surface modification processes of optical materials.
• Establishment of a scientific basis for future research and development aimed at improving the quality and functionality of optical coatings and substrates used in the laser and optical industries.

Potential Applications and Societal Relevance

• Optical and laser industries, in the development and optimization of functional optical coatings for high-energy and ultrafast laser systems.
• Nonlinear photonics, for materials used in optical limiting, laser beam control, and ultrafast optical processes.
• Fundamental and applied research, related to improving the reliability and long-term stability of optical components.

Work Packages

Work Package 1 – Project Management
This work package is focused on the organization, management, and coordination of all project activities. It includes planning of the research program, provision of the necessary resources, preparation of interim and final scientific and financial reports, and coordination among the project participants.

Work Package 2 – Research Part 1: Optical Coatings
This work package focuses on the preparation of thin-film optical coatings and their femtosecond laser modification. Within this package, optimization of laser parameters and initial experimental testing of modification processes for different materials are carried out.

Work Package 3 – Research Part 2: Optical Substrates
This work package is dedicated to the investigation of femtosecond laser modification of glasses and crystals used as substrates for thin-film coatings (fused silica, borosilicate glass, BK7, etc.). The objective is to evaluate the potential for improving their functional properties and their interaction with subsequently deposited coatings.

Work Package 4 – Analytical Evaluation and Characterization
This work package encompasses comprehensive characterization of the materials before and after laser processing. It includes the measurement of linear and nonlinear optical properties, structural and chemical analysis, as well as morphological and topographical evaluation in order to elucidate the mechanisms of modification.

Work Package 5 – Dissemination and Promotion of Results
This work package is devoted to scientific communication and dissemination of the project results through publications in international journals, participation in scientific conferences, provision of publicly accessible research data, and ensuring the online visibility of the project.

Project leader: Assoc. Prof. Dr. Ekaterina Ivanova Iordanova

Principal investigator: Chief Assist. Prof. Dr. Victoria Todorova Atanassova