UV imprinting enabled multi-scale silica-based sol-gel optical components.

Photopolymerizable silica-based sol-gel (SSG) materials with distinct photochemical and optical properties show great promise for fabricating high-performance optical components. However, the development of multi-scale optical components based on SSG materials is significantly limited due to the cracking effect caused by stress accumulation. Herein, to suppress the structural cracking, we introduced methyltrimethoxysilane (MTMS) as a stress-relieving component in the preparation of SSG materials to facilitate the release of internal stress. By further optimizing the MTMS content along with UV exposure parameters, the crosslinking density of the SSG materials was effectively adjusted, thus enabling the fabrication of crack-free optical components via UV imprinting technology. Despite a long process (5-day aging and slow ramping), the low heat-treatment temperature (200°C) avoids traditional sintering (>600°C). Additionally, through shrinkage modeling and compensation strategies, both the surface morphology and dimensional accuracy of the fabricated structures were considerably improved. As a proof-of-concept, two types of optical components with different scales, including centimeter-scale lens arrays and microlens arrays, have been successfully manufactured. The resulting components exhibit improved environmental stability compared to conventional polymer optics, and their optical properties are comparable to those of devices made from conventional materials. This strategy provides a cost-effective approach for producing high-performance multi-scale optical components.