Industrial High-precision 3D Printing via two-photon absorption (TPA) as a potential disruptive tool for microfabrication enables novel products for diverse applications in the field of optics, photonics, biomedicine, and life sciences. Especially the freedom in design provides one-step fabrication of structures that are not feasible with conventional fabrication techniques or need combined technologies with a required changeover of the workpiece.
Up to now, 2PP-fabrication has only been used in the community for structures on the micro and mesoscale due to limited travelling ranges of the translation stages and the field-of-view (FoV) of microscope objectives in combination with galvoscanners to deflect the laser instead of moving the sample relative to the focus. Macroscale elements can be realized via stitching strategies but, however, often induce obvious joints that hinder aimed applications. For this purpose, different fabrication strategies for large scale elements are revealed in this contribution without relying on stitching. Modular machine configurations like inverted focusing through a bath of photoresist (LithoBath3D) enable objects several millimeters in size with micrometer resolution. Additionally, 3D scanning by translation stages only can be efficiently used for the fabrication of large scale DOE structures. For optical elements with high surface quality, precise fabrication is required. As galvoscanners enable high throughput at several 100 mm/s scan speed, TPA-fabricated microlenses are limited to the FoV of the corresponding microscope objective, typically less than 0.5 mm. This limit can be overcome by sophisticated exposure strategies like a synchronized movement of translation stages and galvoscanner (infinite FoV) in combination with advanced beam steering.
Driven by IoT, Industry 4.0, and social media the amount of data to be transferred is tremendously increasing, pushing the need for energy-efficient device concepts for a vast variety of products such as photonic integrated circuits or sensors. Low energy data transfer can be achieved, for example, by replacing part of the electronic circuitry by optical data lines in chip-level packaging, or by introducing optical elements such as specially designed microlenses into semiconductor laser packaging. This also allows to drastically reduce footprints of systems, and – at the same time – to increase functionality. On the other hand, a significant demand is seen in providing lower cost and scalable manufacturing processes with technologies which provide highest flexibility.
High Precision 3D Printing as novel emerging fabrication technology is a promising tool for optical packaging. It enables to reduce the necessary process steps for packaging to only three to five, independently of the packaging task. This is enabled by a novel and versatile packaging concept where the chips and the dies are already mounted prior to the fabrication of optically functional elements such as optical interconnects or microoptics to couple, for example chip-to-chip or dies to fiber, with passive alignment only. Flexible exposure strategies using High Precision 3D Printing provide both, scalability and high throughput with fabrication times from seconds for optical waveguides and single microlenses to only a few minutes for more complex lens systems. The impact of the fabrication strategy will be discussed with respect to the performance of the optical devices.
The fabrication of optical interconnects has been widely investigated for the generation of optical circuit boards. Twophoton absorption (TPA) lithography (or high-precision 3D printing) as an innovative production method for direct manufacture of individual 3D photonic structures gains more and more attention when optical polymers are employed. In this regard, we have evaluated novel ORMOCER-based hybrid polymers tailored for the manufacture of optical waveguides by means of high-precision 3D printing. In order to facilitate future industrial implementation, the processability was evaluated and the optical performance of embedded waveguides was assessed. The results illustrate that hybrid polymers are not only viable consumables for industrial manufacture of polymeric micro-optics using generic processes such as UV molding. They also are potential candidates to fabricate optical waveguide systems down to the chip level where TPA-based emerging manufacturing techniques are engaged. Hence, it is shown that hybrid polymers continue to meet the increasing expectations of dynamically growing markets of micro-optics and optical interconnects due to the flexibility of the employed polymer material concept.