Direct additive manufacturing of transparent fused silica glasses using an integrated paste printing and laser in-situ melting technology

Fused silica glasses are of great importance for applications in optics, photonics, electronics, and biochemistry. However, their harsh processing nature still constrains the design and development of fused silica glasses for advanced applications. Additive manufacturing (AM) is among the promising techniques to improve the fabrication of fused silica glasses. Herein, we develop an integrated paste printing and laser in-situ melting technology to additively manufacture fused silica glasses without post-heat-treatments. For every layer, the fused silica paste was first printed by an air-pumped dispenser based on the predesignated CAD model, and subsequently melted by a CO2 2 laser to become transparent glasses. To improve the paste printing process, the shear thinning property of the developed fused silica paste was investigated to evaluate the printability of the paste, and the control strategy of the paste printing parameters was developed for precise thickness control of the printed paste layer. By optimizing the laser processing parameters, the surface waviness and roughness of the laser-melted glass layers were effectively minimized, indicating the surface uniformity was improved. To evaluate the optical properties of the laser-melted glasses, the optical transmittance and refractive indices of the fused silica glasses melted by different laser powers were characterized. Through stacking the laser-melted fused silica glasses layer- by-layer, three-dimensional (3D) fused silica glass components with unusual thin-wall structures and embedded microfluidic channels have been directly printed, demonstrating that the developed glass AM technology is promising for advanced applications such as microfluidics, integrated optics, and metamaterials.