Direct laser writing based on two-photon polymerization is one of the most advanced techniques to fabricate multifunctionally advanced micro- devices. The voxel is considered as a feature key to control the resolution of the fabricated microstructures. The fabricated voxel can be much smaller than the cube of the laser wavelength, λ³ . To achieve a high resolution, it is known from a long literature that low laser intensity is needed. Oppositely, we introduce a new approach to control the spatial resolution by combining high laser intensity and fast writing speed. By using this approach, a resolution of ~36 𝑛𝑚, e.g. ~1/21 λ, is achieved. In this paper, we investigate on the improvement of the spatial resolution by using a systematic nanofabrication process which we developed. We discuss the factors influencing the resolution, including the laser intensity, the exposure time and the scanning speed by fabricating polymerized- voxels, nanolines and suspended nanofibers connecting two voxels. Lastly, we have fabricated stable 3D microstructures with a sub-diffraction-limit accuracy.

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Yahya Bougdid, Youssef El Idrissi, Imad Maouli, and Zouheir Sekkat, "Direct laser writing of submicrometric voxels in two-photon photopolymerization," Proc. SPIE 11098, Molecular and Nano Machines II, 110980G (Presented at SPIE Organic Photonics + Electronics: August 14, 2019; Published: 30 August 2019); https://doi.org/10.1117/12.2528439.