Postprocessing free 3D printing of glasses for seamless integration in optical microsystems

Integrated optical microsystems are key to next-generation communication, sensing, and quantum technologies, with the potential to exceed the capabilities of conventional microelectronics. Such systems rely on precise control of light, but creating optimal 3D micro-optics is challenging for conventional microfabrication technologies. Multiphoton lithography (MPL) offers nanoscale 3D printing capabilities, while efforts to extend MPL to high-performance glasses typically involve harsh high-temperature or chemical postprocessing that is incompatible with integrated optical microsystems. To address this, we explore the use of hydrogen silsesquioxane (HSQ), an inorganic precursor, for MPL. We demonstrate postprocessing-free 3D printing of solid silica glass and self-forming glass nanogratings with nanoscale resolution. These advances enable the direct integration of glass micro-optics on photonic chips and optical fibers. We present functional 3D-printed glass optical devices, including on-chip ring resonators and photoluminescent sources, and fiber-tip refractive index sensors and polarization beam splitters, opening new avenues for high-performance optical microsystem integration.