Abstract
Microstructuring of glass using laser irradiation has become increasingly important for microsystems technologies, including microoptics. Scaling device dimensions down from millimeters to micrometers is relatively straightforward using glass micromachining [1,2]. A huge variety of methods exist for the fabrication of micro-optical devices, and the choice among them depends on the size and shape of the required features and the materials to be treated. Embossing, injection molding, and similar thermoforming techniques, while providing excellent throughput and cost, are ineffective for glass [3]. Litography techniques require advanced facilities and numerous process steps. A big number of researchers have demonstrated the fabrication of micro-optical elements in glass using electron beam lithography, photolithography, and wet and dry etching [4,5]. These techniques provide high-quality micro-optics systems, however they require very specific and sophisticated working conditions; what increase their cost. In this paper we present a simple, repeatable and non-contaminant method for fabricating microoptical elements by laser ablation and reduction of the roughness of the final structure. Sol-gel is a powerful chemical procedure for obtaining glass-like coatings with suitable properties for a particular application [6]. This procedure allows to improve the optical and morphological properties of microlens arrays previously fabricated. It consists on depositing hybrid SiO2 coatings via sol-gel route onto microlens arrays fabricated using a Ti:Sapphire laser operating at 1030 nm. The applied sol-gel silica layer reduces surface roughness and increases the quality of the spaces between the microlenses generated by the ablation process, thus improving the contrast and homogeneity of the foci of the microlens array. It also improves the scratch and abrasion resistance of the microoptical elements. Microlenses with a diameter of 50 µm and a depth of 1.5 µm have been obtained with the proposed technique.
© 2015 IEEE
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