Fabrication-integrated design for diffractive optical elements
Yunpeng Xu, Zihan Zang, Haoqiang Wang, Yanjun Han, Hongtao Li, Yi Luo, Lai Wang, Changzheng Sun, Bing Xiong, Zhibiao Hao, Jian Wang, Lin Gan
Abstract
Grayscale direct laser writing lithography (DLWL) is a versatile technique for fabricating diffractive optical elements (DOEs), which play a critical role in controlling light across diverse optical applications. However, optical proximity effects (OPEs) during fabrication often lead to discrepancies between the intended design and the actual produced surface, resulting in degraded performance. Here, a fabrication-integrated design (FID) approach is proposed to address this challenge. This approach seamlessly integrates design and fabrication processes to ensure both optical specification and manufacturability. First, this approach models the impact of OPE in DLWL through a highly efficient fabrication simulator, which predicts the DOE surface based on the exposure dose with minimal experimental calibration. Then, a wave optics simulator is employed to evaluate the optical performance of the DOE. Finally, an optimization algorithm iteratively adjusts fabrication parameters to minimize discrepancies between the desired and simulated optical outcomes. The FID approach demonstrates significant improvements in DOE performance. For instance, it achieves more than 25% reduction in unwanted diffraction orders for diffractive beam splitters. Additionally, it improves the quality of digital holograms and the performance of extended depth-of-focus imaging. Our implementation of the FID approach can support the design of very large-scale DOEs with up to 100 million pixels. These results highlight the effectiveness of the FID approach in producing high-quality optical elements, offering broad benefits for applications in imaging, sensing, and display technologies.