In this paper, we characterize the femtosecond laser filament-fringes in titanium. In order to fabricate regular arrays of filaments, we place either a pinhole or a beam shaper in the optical path of the femtosecond laser beam that originates linear diffraction of the laser beam. Soda-lime glass is used as Kerr medium to produce the filaments. As a consequence, the intensity distribution of the laser beam is modulated and fringe type of filament distributions is evident. The suitable control over the size of the diaphragms (pinhole or beam shaper) leads us to adjust the shape, orientation, and number of filaments in each irradiated spots in titanium sample. By properly adjusting the diameter of a pinhole that was placed in the optical path, we are successful in forming a single filament in titanium. By using these single filaments, we fabricated high aspect ratio periodic holes in the titanium surface by moving the translation stage in both horizontal and vertical directions. The period of the holes in the horizontal direction is controlled by varying the scanning speed, whereas the period in the vertical direction is controlled by varying the vertical scanning step. We strongly believe that, filamentation technology described in this paper will have applications in forming a variety of micro/nano-structures in various materials.
In this paper, we report on the formation of micro/nano-fluidic channels inside fused silica glass using single-beam femtosecond laser. The micro/nano-fluidic channels are fabricated by controlling the irradiation conditions of the femtosecond laser pulses, especially, pulse energy and scanning speed. We examine the production of this kind of channels both in air and water. In both cases, laser beam is focused inside the glass bar and shined horizontally with very low scanning speeds. In case of water, the glass sample is placed inside distilled water, which way is expected to reduce the surface roughness of the channels. The quality of the channels fabricated under different environment is compared as well. We further investigate the influence of various laser parameters on the production of channels. We also evaluate the fluid flowing ability of the fabricated micro/nano-fluidic channels of various diameters, fabricated under different environment and irradiation conditions.