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The systems for multiphoton 3D nanoprinting are rapidly increasing in print speed for larger throughput and scale, unfortunately without also improvement in resolution. Separately, the process of photoinhibition lithography has been demonstrated to enhance the resolution of multiphoton printing through the introduction of a secondary laser source. The photo-chemical dynamics and interactions for achieving photoinhibition in the various multiphoton photoinitiator systems are complex and still not well understood. Here, we examine the photoinhibition process of the common photoinitiator 7-diethylamino 3-thenoylcoumarin (DETC) with inhibition lasers near or at the multiphoton printing laser wavelength in typical low peak intensity, high repetition rate 3D nanoprinting processes. We demonstrate the clear inhibition of the polymerization process consistent with a triplet absorption deactivation mechanism for a DETC photoresist as well as show inhibition for several other photoresist systems. Additionally, we explore options to recover the photoinhibition process when printing with high intensity, low repetition rate lasers. Finally, we demonstrate photoinhibition in a projection multiphoton printing system. This investigation of photoinhibition lithography with common photoinitiators elucidates the possibility for photoinhibition occurring in many resist systems with typical high repetition rate multiphoton printing lasers as well as for high-speed projection multiphoton printing.

 

Abstract There is demand for scaling up 3D printing throughput, especially for the multi-photon 3D printing process that provides sub-micrometer structuring capabilities required in diverse fields. In this work, high-speed projection multi-photon printing is combined with spatiotemporal focusing for fabrication of 3D structures in a rapid, layer-by-layer, and continuous manner. Spatiotemporal focusing confines printing to thin layers, thereby achieving print thicknesses on the micron and sub-micron scale. Through projection of dynamically varying patterns with no pause between patterns, a continuous fabrication process is established. A numerical model for computing spatiotemporal focusing and imaging is also presented which is verified by optical imaging and printing results. Complex 3D structures with smooth features are fabricated, with millimeter scale printing realized at a rate above 10 −3 mm 3 s −1 . This method is further scalable, indicating its potential to make fabrications of 3D structures with micro/nanoscale features in a practical time scale a reality.