Towards Scalable Aligned Two-Photon Lithography for Photonic Integration

This paper presents advancements in aligned two-photon lithography (A2PL), where high resolution laser-based 3D fabrication technology is combined with high precision alignment routines. We demonstrate both camera- and confocal-based 3D detection algorithms for high-precision alignment, achieving accuracies below 100 nm. Two-photon lithography is utilized to fabricate photonic components such as micro-lenses for fiber-to-chip coupling, with losses as low as 1.7 dB and out-of-plane coupling structures. The workflow is readily adapted to other applications and material platforms, enabling scalable additive and multi-material fabrication.