Advanced manufacturing techniques for wafer-level freeform micro optics with high refractive index

Scaling up from prototype to high volume manufacturing is a challenge for many technologies. In particular for waferlevel manufacturing of advanced freeform micro-optics, there is a gap which needs to be addressed. The combination of two-photon grayscale lithography (2GL), step and repeat nanoimprint lithography (S&R NIL) followed by SmartNIL® replication enables to expand design freedom while still being able to scale up from prototype to high volume manufacturing. This entire process flow was used to pattern microstructures with challenging freeform geometries which are required for emerging devices and applications across the photonics market. Additionally, to further increase the flexibility and performance of the devices, it is possible to use advanced high refractive index materials, which, so far, have been limited to applications in sub-micrometer thin layers, for freeform micro-optics and micro lens arrays. The results presented in this work provide an overview of the versatility and recent achievements of NIL in terms of structure sizes and shapes using different imprint resins to obtain even more design flexibility for freeform micro-optics and micro lens arrays.