This paper demonstrates 3D printing of solid silica glass with sub-micrometer resolution without sintering. This is achieved by locally crosslinking hydrogen silsesquioxane (HSQ) using nonlinear absorption of sub-picosecond laser pulses. The as-printed glass, while optically transparent, exhibits photoluminescence and a high ratio of 4-membered silicon-oxygen rings. Annealing at 900 °C yields glass indistinguishable from fused silica. The technique's utility is shown by creating an optical microtoroid resonator, a luminescence source, and a suspended plate on an optical fiber tip, suggesting applications in photonics, medicine, and quantum optics.

Po-Han Huang, Miku Laakso, Pierre Edinger, Oliver Hartwig, Georg S. Duesberg, Lee-Lun Lai, Joachim Mayer, Johan Nyman, Carlos Errando-Herranz, Göran Stemme, Kristinn B. Gylfason, Frank Niklaus