Angle of incidence dependence of copper reflectivity and absorption coefficient under femtosecond pulsed laser irradiation
In this paper, we determined the dependence of copper reflectivity and absorption coefficient with the angle of incidence under femtosecond pulsed laser irradiation using two-temperature model. We found that the behavior of reflectivity as function of angle of incidence remains the same, but the magnitude decreases as the laser pulse hits the copper owing to the enhanced absorption. The absorption coefficient decreases as the laser pulse hits the copper but increases with angle of incidence, indicating that energy is confined in the surface. We also found that reflectivity from p-polarized light tends to be lower than s-polarized light, which can be due to resonant absorption. This study can give us more detailed insight on how the femtosecond laser pulse affects the optical properties of the copper.