Recently, the authors demonstrated the self-assembly of optical microwires using convective flow within a drop of water-based suspension of silica nanoparticles on flat glass substrates. The main purpose of this Optics Materials Express paper is to use laser processing techniques to improve the formation of these optical microwires. A brief description of the authors’ method is as follows. First, the authors employed a UV laser with a wavelength of 193 nm to alter the surface properties of borosilicate slide. By changing the laser fluence and the separation between scanning lines, the authors could control the morphological profile of the slides, resulting in a change in the contact angle exceeding 25°. Next, by selectively producing surface structures on the slides, the authors were able to convert the shape of the drop on the slide surface from a spherical caplet to an approximate ellipsoid caplet by inducing asymmetric contact angle distribution, and tailor the convective flow within the drop so that the radial stresses within the caplet are focused at two points. This tailoring of convective flow eventually led to the formation of the optical microwires more uniformly.
Overall, the authors suggested a new method of controlling the fabrication of the optical microwires with the help of a laser processing technique. However, the main discovery of this paper is not limited to the improvement of fabrication of the optical microwires. This research may be able to open up a new direction of microfluidics combined with laser processing, since sophisticated control of liquid flow on a surface can be achieved through surface structuring with laser irradiation.
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