Closed-loop high-precision two-photon lithography based on a multiplexed single-cavity dual-comb laser

Two-photon lithography fabricates three-dimensional structures with 100-nanometer resolution; yet its industrial adoption is hindered by poor reproducibility and the need for complex manual tuning processes. While post-fabrication metrology, such as scanning electron microscopy, characterizes final morphologies, it cannot prevent manufacturing errors. Here we show a two-photon lithography platform powered by a single-cavity dual-comb laser that addresses this limitation through real-time correction. During fabrication, one laser comb, after frequency conversion, performs two-photon printing, while the dual-comb system simultaneously performs in-situ phase measurements across the full work field at 360 hertz. By feeding the phase profiles into a dynamic model, the platform automatically modulates printing parameters to correct height errors. We demonstrate this capability through a continuous 14-hour fabrication process to manufacture different millimeter-scale diffractive optical elements with less than 100-nm absolute errors. The resulting devices exhibit superior signal-to-noise ratios, process repeatability, and focus quality. This closed-loop dual-comb platform offers a cost-effective, scalable solution for high-precision, high-yield nanomanufacturing.