Enhanced Absorption Of Metals Over Ultrabroad Electromagnetic Spectrum By Femtosecond Laser Processed Micro-nano Structures

Femtosecond laser inducing micro-nanostructures on metal surface can enhance the surface electromagnetic wave absorption capacity,the surface preparation obtained microstructure by such micro-fabrication methods compared with the conventional electromagnetic wave absorbing material,it has thin, not falling, temperature and environmental protection features. This technology opens up a new way for people to study electromagnetic wave absorption material.This thesis we processed micro-nanostructures on the metal Ti, Al, Fe, Ni surface by femtosecond laser and studied its absorption characteristics of electromagnetic waves. First, we studied a ultrabroad spectral for high absorption of light micro-nanostructures preparation and research, the sample in the visible to near-infrared reflectance show that Ti, Al sample in the visible absorption rate over95%, while in the infrared absorption rate over90%. Also, we use a scanning electron microscope (SEM) of the sample micro-nanostructures were observed. According to the morphology of the sample, we use the finite difference time domain (FDTD) method for the numerical simulation of the grating structure calculations and combined with the simulation results on the absorption mechanisms were discussed and explained. With a micro-nanostructure surface in the microwave absorption properties of research, we prepared micro-nanostructures in different types of metal surfaces by femtosecond laser, and Ni was prepared for different types of micro-nanostructure(one-dimensional periodic microstructure, two-dimensional array structure and nanostructures). The samples were measured reflectivity from0.1to18GHz by vector network analyzer. We found that the micro-nanostructures on metal surface by femtosecond laser prepared have not obvious broad spectrum absorption for microwave band, but the absorption of a specific wavelength is relatively obvious.