Lawrence Livermore National Laboratory (LLNL) engineers and scientists, in collaboration with Stanford University, have demonstrated a breakthrough 3D nanofabrication approach that transforms two-photon lithography (TPL) from a slow, lab-scale technique into a wafer-scale manufacturing tool without sacrificing submicron precision.
Published today in Nature, the team's TPL platform uses large arrays of metalenses - engineered, ultrathin optical elements - to split a femtosecond laser into more than 120,000 coordinated focal spots that write simultaneously across centimeter-scale areas. The metalens-based method produces intricate 3D architectures with minimum feature sizes of 113 nanometers and achieves throughput more than a thousand times faster than commercial systems.
"When the 3D printing system started to work at one-centimeter scale and then three-centimeter scale for the first time, it was really amazing to see the idea that was developed for three to four years at that time come true," said Xiaoxing Xia, an LLNL materials engineer and principal investigator. "To see a print being done accurately at speed hundreds to thousands of times faster than our commercial printer, we realized a breakthrough has happened."
From niche laboratory technique to scalable manufacturing
For years, TPL has been valued for its nanoscale resolution, but its reliance on microscope objectives confined the printable area to a few hundred microns. Anything larger required stitching thousands of tiles together, a slow process that introduced alignment errors and prevented TPL from leaving the laboratory.
The team's metalens TPL approach replaces the microscope objective with a tiled array of high-numerical-aperture metalenses, each one acting as a miniature printer. Instead of scanning a single beam, the system prints thousands of small regions in parallel, and all regions merge seamlessly in the same pass. By spacing focal spots at the metalens pitch rather than crowding them into a tiny optical field, the system avoids the proximity effects that plagued earlier multi-beam approaches.
"It means TPL finally has the potential for industry adoption," said Songyun Gu, a postdoctoral researcher at LLNL and the first author on the paper. "Previously it was purely an experimental tool for researchers. With wafer-scale nanomanufacturing, we have the potential to make nanomaterials and microdevices the same way we make computer chips, which are highly complex but can be made in volume at very low unit cost. And meta-optics is exactly the solution."
Adaptive light control unlocks new design freedom
To print structures that are not fully periodic, the team integrated a spatial light modulator that adjusts the intensity of each focal spot in real time. The system can switch beams on or off, tune linewidths with grayscale control and choreograph beams to form larger patterns layer by layer. What began as a way to equalize beam intensity unexpectedly opened the door to far more general design freedom.
"During the project, we realized that by dynamically switching the focal spots on and off and carefully planning the printing trajectory, we can actually print fully stochastic structures with a high degree of parallelization," Xia said. "Songyun [Gu] and [co-author] Sarvesh [Sadana] printed 16 different microscopic chess openings in one process." The team named the method Adaptive Meta-Lithography to acknowledge extensive support from LLNL's Advanced Manufacturing Laboratory.
The parallel, yet adaptive approach allows metalens TPL to fabricate everything from gradient density laser targets and flexible terahertz devices to tens of millions of micro-particles per day. It also enables the creation of complex modular architectures for emerging technologies in microfluidics, quantum information, microelectronics, photonics, fusion energy and biomedicine. Particularly exciting to researchers is the potential in scaling up LLNL's ongoing, transformative R&D efforts on 3D printing fusion fuel capsules and trapped-ion quantum computing chips.
Xia sees the convergence of optics and additive manufacturing as a defining step for the field. "Light is the finest chisel on earth to craft functional materials and micro-architectures," he said. "New ways to control light will revolutionize how to make materials."
As higher-power lasers, larger metalens wafers and faster modulators become available, the team believes metalens TPL will be able to print even more complex devices at far greater speeds, pushing 3D nanomanufacturing toward mainstream, wafer-scale production. This technology platform, named MetaLitho3D, recently won a 2025 R&D 100 Award, indicating the potential for industry adoption to solve real-world problems.
Other co-authors include LLNL's Anna Guell Izard, Dongping Terrel-Perez, Sijia Huang, Travis Massey, Alex Abelson, Magi Mettry-Yassa, Wonjin Choi and Thejaswi Umanath Tumkur; Stanford's Chenkai Mao, You Zhou and Jonathan Fan; and Caltech's Wenjie Zhou, Hujie Yan, Ziran Zhou and Chiara Daraio.
