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- Migal, E. A., et al.
(author)
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Role of deposited energy density and impact ionization in the processes of femtosecond laser-matter interaction in solids: scaling from visible to mid-IR
- 2019
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In: Nonlinear Optics and Applications XI. Proceedings Vol. 11026. SPIE OPTICS + OPTOELECTRONICS, 1-4 April 2019. - : SPIE. - 9781510627192
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Conference paper (peer-reviewed)abstract
- The deposited energy density (DED) serves as a key parameter in the process of the femtosecond laser pulse energy delivery into the bulk of transparent dielectrics. The laser-induced micromodification can be created if the value of DED exceeds a certain threshold, which is specific for each material and does not depend on the laser wavelength. In this contribution, we present a comprehensive study of the DED evolution with the driving pulse energy and wavelength under femtosecond microstructuring of transparent dielectrics. To precisely determine the laser impact area we applied for the first time a real-time diagnostic of microplasma based on third harmonic generation. This technique gives submicron spatial resolution and is extremely sensitive to the free electron density (about 10(-5) of the critical electron density). We found out that the threshold DED equals to approximately 2.5 kJ/cm(3) for fused silica and roughly corresponds to excess of glass transition temperature. The highest DED is achieved for the shortest wavelength (620 nm) and equals to 16 kJ/cm(3).
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