Colorful and superhydrophobic titanium surfaces textured by obliquely incident femtosecond laser induced micro/nano structures

Multiscale micro/nano structures (e.g. large period ripples and sputtered particles) on titanium surfaces by obliquely incident femtosecond laser texturing. The effects of laser incident angle on surface structures, wettability and structural color were studied. As a result, sputtered particles are formed on the titanium surface for all incident angle. Fine ripples are appeared on the large period ripples, when the incident angle is greater than 50 degrees. However, there is no fine ripples structure when the incident angle is less than 50 degrees. Meanwhile, the structured surfaces appear structural color and superhydrophobicity for all laser angle. The formation mechanism of hybrid micro/nano structures on the titanium surface is also discussed.