Wafer-Scale Nano-Fabrication of Multi-Layer Diffractive Optical Processors

LOS ANGELES - Aug. 11, 2025 - PRLog -- Researchers at the UCLA Samueli School of Engineering, in collaboration with the Optical Systems Division at Broadcom Inc., reported a broadband, polarization-insensitive unidirectional imager that operates in the visible spectrum, capable of high-efficiency image transmission in one direction while effectively suppressing image formation in the reverse direction. This device incorporates diffractive structures fabricated through wafer-scale lithography on high-purity fused silica, offering high optical transparency, thermal stability and ultra-low loss.

Diffractive optical processors and metasurfaces play a significant role in advanced optical computing and computational imaging. Despite the promising potential and emerging uses of diffractive optical processors and metamaterials, most of these demonstrations remain constrained to 2D implementations and longer wavelengths due to the fabrication challenges of nanoscale features in 3D diffractive architectures.

UCLA and Broadcom researchers demonstrated that their nano-fabrication approach, along with deep learning-based inverse design, enables visible image formation in only one direction—transmitting images from the input field of view (A) to the output field of view (B)—while blocking and distorting image formation in the reverse direction (B to A). This work represents the first demonstration of broadband unidirectional imaging in the visible spectrum, achieved with nanoscale, polarization-insensitive diffractive features that were optimized using deep learning.

Notably, the high-throughput fabrication process leverages methods compatible with semiconductor manufacturing, opening the door to seamless integration with optoelectronic components. This work marks a significant stepping-stone for future advances in computational imaging, optical sensing, and optical information processing, with potential applications in compact multispectral imagers and optical privacy protection.

The research was conducted by a team from the UCLA Electrical and Computer Engineering Department and the California NanoSystems Institute at UCLA, in collaboration with the Optical Systems Division at Broadcom Inc.

Paper: https://doi.org/10.1038/s41377-025-01971-2