Reflectance of thin silver film on the glass substrate at the interaction with femtosecond laser pulses

31st International Conference on Equations of State for Matter

Petrov, Yu V.^1,2 ; Khokhlov, V.A.^1 ; Inogamov, N.A.^1 ; Khishchenko, K.V.^3 ; Anisimov, S.I.^1

Landau Institute for Theoretical Physics, Russian Academy of Scienses, Akademika Semenova 1a, Chernogolovka, Moscow Region

142432, Russia^1

Moscow Institute of Physics and Technology, Institutskiy Pereulok 9, Dolgoprudny, Moscow Region

141700, Russia^2

Joint Institute for High Temperatures, Russian Academy of Sciences, Izhorskaya 13 Bldg 2, Moscow

125412, Russia^3

关键词: Collision frequency;    Conduction electrons;    Dielectric permittivities;    Electron-electron collisions;    Hydrodynamic equations;    Kretschmann configuration;    Thermodynamic state;    Thermodynamics and kinetics;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/774/1/012099/pdf
DOI  :  10.1088/1742-6596/774/1/012099

来源: IOP

【 摘 要 】

The optical response of thin silver film (of 60 nm thickness) coated on a glass prism (Kretschmann configuration) and heated by the femtosecond laser pulse of small intensity is investigated by the computational modeling. We have calculated the reflectance of p-polarized probe laser beam when it is incident onto the metal film from the glass side. Reflectance is calculated at incidence angles close to the surface plasmon resonance angle. We have considered first 100 ps after the action of femtosecond laser pulse onto the film surface. Changes in thermodynamic state and hydrodynamic motion of film material are described by the system of hydrodynamic equations taking into account different temperatures of electrons and ions (two- temperature state) and consequently two-temperature thermodynamics and kinetics at such early times. These changes define the changes in electron-ion and electron-electron collision frequencies. The collision frequencies of conduction electrons, being calculated in dependence on the density and electron and ion temperatures, allow us to find the Drude part of dielectric permittivity. Together with the interband contribution it gives possibility to calculate reflectance depending on the state of metal surface. It is shown a great importance of electron-electron interactions in the temporal behavior of reflectance at early times of laser-film interaction.