Enhancing microwave absorption of metals by femtosecond laser induced micro/nano surface structure

It is well known that microwave radiation can be almost completely reflected by all the smooth metal surfaces. In this paper, we show, for the first time, that structured metal surface by femtosecond laser can largely reduce microwave reflectivity from the surface with absorption peaks in the range from 10 to 18 GHz. Our experimental results further show that blueshift of the microwave absorption peaks can be realized by different femtosecond laser scanning modes. The structured metal surface offers many advantages such as with thin thickness, high thermal stability and structural rigidity over the traditional microwave absorption technology based on nanoscale particles coatings. This technique provides a new approach for the reduction of microwave reflectance from metal surface.