Adaptative additive fabrication of parallel, high-performing 3D integrated optical interconnects

Additive fabrication, in particular direct-laser writing (DLW) combined with two-photon polymerization (TPP), stands out as an innovative tool for creating intricate 3D photonic components. However, the long fabrication time associated with DLW-TPP restricts large-scale implementations. Here, we introduce an adaptative lithography strategy, i.e. flash-TPP, combining one- (OPP) and TPP, while adjusting the resolution of the different sections of the photonic circuit, reducing the printing time by up to 90% compared to TPP-only. Via flash-TPP, we demonstrate the fabrication of polymer-cladded single-mode photonic waveguides and adiabatic splitters, with low 1.3 dB/mm (0.26 dB) propagation (injection) losses and record optical coupling losses of 0.06 dB with very symmetric (3.4 %) splitting ratios for adiabatic couplers. The scalability of output ports here addressed can only be achieved by using the three spatial dimensions, which is challenging in 2D.