A Comparison of Characteristics of Periodic Surface Micro/Nano Structures Generated Via Single Laser Beam Direct Writing and Particle Lens Array Parallel Beam Processing

Changing material surface micro/nano structures using laser beam texturing is a valuable approach in wide applications such as control of cell/bacterial adhesion and proliferation, solar cells and optical metamaterials. Here we report a comparison of the characteristics of surface micro/nano structures produced using single beam laser direct writing and particle lens array parallel laser beam patterning. A Nd:YVO4 nanosecond pulsed laser at 532 nm wavelength was used in the laser direct writing method to texture the stainless steel surface submerged in water and in air with different scanning patterns. Changes in surface morphology, wettability, surface chemistry and optical reflectivity were analyzed. In the particle lens array method, an excimer nanosecond laser at 248 nm wavelength was adopted to produce surface patterns on GeSbTe (GST) film coated on a polycarbonate substrate by splitting and focusing a single laser beam into millions of parallel breams. Single beam laser direct writing shows that the surface of high roughness and oxygen percentage content presented high wettability and low reflectivity characteristics. However, the controllability of the type of surface micro/nano patterns is limited. The parallel laser beam processing using particle lens array allows rapid production of user designed periodic surface patterns at nano-scale overcoming the optical diffraction limit with a high degree of controllability. Controlling the uniformity of the particle lens array is a challenge.