Additively Manufactured Vertical Photonic Interconnects

We propose to develop a cost-effective additive manufacturing platform for fabricating high-density photonic bump bonds that will transform next-generation three-dimensional (3D) photonic integrated circuits (PICs). Modern PICs demand efficient, low-loss vertical interconnects that overcome the inherent limitations of grating couplers, photonic wire bonds, and free-space coupling. Our innovative approach leverages scalable femtoliter (fL) inkjet printing combined with advanced nanocomposite materials to directly print photonic bump bonds with sub-micron alignment tolerances (<200 nm) and insertion losses below 0.1 dB per facet. Central to our technology is the integration of advanced metasurfaces and graded-index (GRIN) optical channels, which enable relaxed-tolerance vertical coupling and dramatically improve mode matching while reducing scattering losses. Rigorous multiphysics simulations, together with comprehensive experimental characterization—using FTIR spectroscopy, ellipsometry, and digital holographic microscopy—will validate the broadband performance of our prototypes. This integrated strategy addresses critical challenges in vertical photonic integration and establishes a foundation for scalable, high-yield PIC manufacturing.