Three-dimensional (3D) printing has been a hallmark of manufacturing for diverse applications in the last decade, from larger needs in the construction and aerospace industries to those as precise as quantum computing chips or target capsules for fusion experiments at the National Ignition Facility (NIF). However, a persistent problem with 3D printing across all industries is the speed of printing—to print with high resolution and precision has historically required extremely long print periods, and to print with faster speed sacrifices resolution and accuracy.
Two-photon lithography (TPL) is the highest resolution 3D printing method in existence today, with a minimum feature size of 100 nanometers enabling control over most structural attributes of a material. Yet, despite the excellent precision of TPL, it falls victim to the same tradeoff as other 3D printing types and prints at unfavorably slow speeds. For applications such as potential inertial fusion energy (IFE) power plants, where target capsules are used at rates of more than 100,000 per day, a slow printing speed cannot keep up. “I’ve been using two-photon 3D printing for more than 10 years,” says Xiaoxing Xia, a staff scientist in Livermore’s Materials Engineering Division (MED). “It’s an excellent technology that can provide high-resolution and accurate printing, but the problem is that it is just too slow to make a real impact in our day-to-day lives.”
Parallelization, or breaking the TPL process down into smaller parts printed simultaneously, offers an opportunity to drastically decrease print time while maintaining precision, either by printing multiple small products or smaller sections of a larger product at the same time. Xia and a team of Laboratory researchers tapped into the parallelization concept to improve TPL speeds, culminating in the 2025 R&D 100 Award–winning technology metaoptics-enabled large-scale 3D nanolithography (MetaLitho3D). The technology is a compelling 3D-printing platform that offers a thousand-fold increase in speed over conventional single objective TPL methods on the market while maintaining ultrahigh resolution—a truly cutting-edge invention.
A Combined Effort
To achieve such a breakthrough, the team made use of a recent development in the nanophotonics community: metalenses, which are lenses made from subwavelength nanostructures carefully designed and arranged to achieve specific properties. (See S&TR, April/May 2025, Pushing Matter to the Extreme.) Researchers incorporated an innovative metalens array—120,000 metalenses adjacent to one another in a 3.5-by-3.5-centimeter arrangement, with a thickness of 1 micrometer—designed by collaborators at Stanford University for TPL printing to replace conventional optics that rely on bulky media to bend light. Each metalens consists of ensembles of subwavelength phase-shifting elements that provide extraordinary wavefront shaping capability, and hundreds of thousands of lenses work in tandem to create a final printed part.
To use this large metalens array for parallel fabrication, a photosensitive material is sandwiched between the metalenses and a fabrication substrate. Unlike other TPL methods, the laser in MetaLitho3D points through the array of metalenses and generates a focal spot through each one, patterning individual substructures on the substrate that are automatically stitched to adjacent substructures. Stitching—ensuring one substructure picks up precisely where the neighboring substructure left off—is a common hurdle in conventional TPL that sequentially prints these building blocks one after another accumulating errors at each step. MetaLitho3D, in contrast, prints simultaneously with hundreds of thousands of miniature lenses that are precisely fabricated on one wafer, enabling a controlled print of even bulk parts with a population of print regions with equivalent robustness to that of a single print.
For increased reliability and precision, Liliana Dongping Terrel-Perez, a staff scientist in the Laboratory’s Computational Engineering Division, devised a method to use a spatial light modulator to control the illumination condition on each metalens. MetaLitho3D also has the capability to actively pattern the focal spot array during substrate scanning, enabling the rapid production of aperiodic 3D structures, functional devices, and systems.
The team has already demonstrated its versatility by fabricating replicated microstructures, centimeter-scale continuous 3D nanoarchitectures, large probe arrays, and metamaterials. In one test case, the team printed an object with a thickness of 0.3 millimeters and an area of 9 square centimeters in about two hours. The same object would have taken approximately three months to print using commercial TPL printers. “We are a small, purely Laboratory Directed Research and Development (LDRD)–funded team, whereas traditionally I think of these winning technologies as coming from larger programmatic teams with stable funding,” says Xia. “I’m very grateful to the members of our team, who each contributed tremendously to bring this technology to life.”
Next-Generation Printing
The team’s efforts have resulted in a transformative nanolithography platform with unprecedented fabrication capabilities in scale, resolution, and quality, meeting the market need for high-resolution, high-throughput fabrication of wafer-scale components, devices, and systems for a variety of applications. “I truly believe what we do is impactful because we’re disrupting the paradigm of how nanoprinting has been done,” says Gu, a postdoctoral researcher in MED who led the experimental development of the printing system that enabled the high printing quality of MetaLitho3D. Adds Terrel-Perez, “I feel honored to have earned an R&D 100 Award with the team. We are doing world-class science and technology, and the hard work and persistence, especially of Xiaoxing (Xia) and Songyun (Gu) has definitely paid off.”
In addition to one patent and three ongoing patent applications, the team is putting together an LDRD Strategic Initiative proposal to leverage MetaLitho3D for a target fabrication foundry to enable inertial fusion energy (IFE) target production in larger volumes. They also hope to continue improving Laboratory capabilities for metalens array fabrication to enable in-house production. “The biggest application driven by the mission of the Laboratory is to mass produce fusion targets for IFE, and that’s one area in which we can be immediately impactful,” says Xia. Adds Gu, “I’m very excited about the MetaLitho3D technology being recognized, and I think it will benefit the entire research field in big ways.”
—Lilly Ackerman
For further information contact Xiaoxing Xia (925) 423-6489 (xia7 [at] llnl.gov (xia7[at]llnl[dot]gov)).
