Chinese team cuts metalens fabrication to 15 minutes with new photoresist

Researchers in China developed a one-step nanoimprint process for achromatic metalenses that works across 480-640 nm and uses a new photoresist with high refractive index, high transmittance and low shrinkage. The method could make compact imaging and photonics devices easier and cheaper to mass-produce.

Why it matters: - Achromatic metalenses could shrink imaging systems while reducing chromatic aberration. - A faster, scalable fabrication method addresses two major barriers to commercialization: low throughput and high production cost. - The approach may support future compact imaging, augmented reality displays and integrated photonics.

What happened: - Chinese researchers reported a one-step nanoimprint lithography process for achromatic metalenses in Light: Advanced Manufacturing. - The work was led by Professors Nan Zhang of Beijing Institute of Technology and Wanjiao Zhang of the University of Chinese Academy of Sciences. - The metalenses operate across the 480-640 nm band. - The original source DOI is 10.37188/lam.2026.105.

The details: - The team developed a hybrid photoresist based on an acrylate polymer matrix with TiO₂ nanoparticles. - The resist reached a refractive index of 1.92-1.97 and transmittance above 99% over 480-640 nm. - The material limited lateral and vertical shrinkage to 5.19% or less. - The TiO₂ nanoparticles were uniformly dispersed, with an average particle size of about 26 nm. - The nanoparticle size stayed below the minimum feature size, which helped the resist fill the imprint features completely. - The researchers used silane and methacryl-functionalised silane as shrinkage inhibitors. - Those additives strengthened bonding between the inorganic phase and polymer matrix and helped control the crosslinking network. - A UV-curable resin formed the working stamp in 3 minutes under a 300 W UV lamp. - Automated fabrication completed the working stamp in under 10 minutes. - The imprinting, exposure and demoulding steps took another 5 minutes. - The full stamp-to-metalens workflow took 15 minutes. - The working stamp is reusable. - Measurements with SEM and FIB-SEM tracked nanopillar dimensions in the master, working stamp and final samples. - Average shrinkage was 2.23% for width, 1.87% for length and 3.47% for height. - Maximum shrinkage did not exceed 5.19%. - The fabricated metalens showed focal-length deviation below 2% across 480-640 nm. - The focal spot size stayed close to the diffraction limit. - Simulations adjusted with measured dimensional deviations matched the experimental results closely. - The National Natural Science Foundation of China funded the work under grant 62575023.

Between the lines: - The main advance is not just optical performance. It is the combination of optical quality, dimensional fidelity and speed. - Traditional electron-beam lithography can make fine structures, but it is too slow for mass production. - Deep-UV lithography is scalable, but it usually requires expensive tools and more complex steps. - Existing nanoimprint resists have often shrunk by as much as 20% after curing, which can distort optical devices. - This result suggests nanoimprint lithography can move closer to practical metalens manufacturing if material shrinkage stays low.

What's next: - The researchers say the method offers a practical route for high-precision, high-efficiency, large-scale production of achromatic metalenses. - The team points to applications in compact imaging, augmented reality displays and integrated photonics. - Further work will likely focus on scaling the process and testing device performance in real products.