Spatially confined photoexcitation of the photoresist is essential to achieve a high spatial resolution for stereolithography and related 3D printing; while for the photopolymerization initiated by conventional organic dyes based on one photon absorption, it is impossible to achieve localized excitation due to the linear correlation between excitation power and excited state concentration; usually, all the molecules in the whole beam path were excited. Photon upconversion technology provides the possibilities for spatially confined photoexcitation to achieve high spatial resolution due to the nonlinear optical characteristics. Three different upconversion technologies have been employed to assist the photopolymerization process. This review was organized according to the mechanisms of the upconversions and summarized the progress of stereolithographic 3D printing enabled by two-photon absorption, upconversion nanoparticles, and triplet-triplet annihilation, the research progresses in the last two years were specially emphasized.

光致抗蚀剂的空间受限光激发对于实现立体光刻和相关 3D 打印的高空间分辨率至关重要；而对于传统有机染料基于单光子吸收引发的光聚合，由于激发功率与激发态浓度之间的线性相关性，无法实现局域激发；通常，整个光路中的所有分子都被激发。光子上转换技术由于非线性光学特性，为空间受限光激发实现高空间分辨率提供了可能性。已采用三种不同的上转换技术来辅助光聚合过程。