Two‐photon polymerization is a powerful method for three‐dimensional (3D) precision nanofabrication. To facilitate the fabrication speed, for the first time, single‐exposure or single‐scan two‐photon polymerization of an arbitrary 3D microstructure with smaller or larger volume is demonstrated through focal field engineering. The constraints and the initial conditions of the Gerchberg–Saxton algorithm for the retrieval of the incident wavefront are adapted for the shape fidelity and the smoothness of the 3D focal field intensity distribution. As a result, a small 3D microstructure can be polymerized by a single exposure within 0.1 s, while a larger one can be formed by continuous polymerization of slices of the structure with one‐dimensional single scan with a speed of 6 µm s−1. The microlenses that generate vortex beams with different orbital angular momentums are polymerized to demonstrate the high fabrication precision. These pave the way for the rapid two‐photon polymerization of arbitrary 3D structures.

Metallic helical metamaterials have become the prominent candidates for circular polarizers and other optical-chiral devices as they exhibit strong circular dichroism at a broad operation bandwidth. However, the rapid fabrication of an intertwined double helix with multiple pitch numbers and excellent mechanical strength, electrical conductivity and surface smoothness remains a challenge. We propose and realize the single-exposure femtosecond laser photoreduction of a freestanding, three-dimensional silver double-helix microstructure by the double-helix focal field intensity engineered with a spatial light modulator. At the same time, the photoreduction solution and the laser repetition rate are optimized to further tackle the surface roughness and the thermal flow problems. As a result, the silver double-helix array with the enhanced quality exhibits pronounced optical chirality in a wide wavelength range from 3.5 to 8.5 μm. This technique paves a novel way to easily and rapidly fabricate metallic metamaterials for chiro-optical devices in the mid-infrared regime.

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