Femtosecond laser blackening of metals

Abstract

Using a femtosecond laser processing technique, we produce technologically important black metals (Au, W) and black Ti90/Al6/V4 alloy with absorptance of about 85–95% over a broad wavelength range from ultraviolet to infrared. From scanning electron microscopy we find that the enhanced absorption of the black metals is caused by a rich variety of nano- and microscale surface structures. The black metals produced in our study may find applications in photonics, plasmonics, stealth technology, airborne/spaceborne devices, broadband thermal radiation sources, solar energy absorbers, radiative heat transfer devices, thermophotovoltaics, and biomedicine.