Fig. 1. (Color online) Schematic diagram of two-step-STED light confining mechanism for LMC-MPL (Energy level transitions include: 3hν three-photon absorption, IC internal conversion, VR vibrational relaxation and ISC inter-system crossing. Q: quencher, [Q]*: excited quencher, R*: free radical, Q–R: non-reactive adduct formed by free radicals and quencher)^[1].

Fig. 2. (Color online) Three-dimensional woodpile structure made by MPL, MC-MPL, and LMC-MPL. (a)–(c) are taken perpendicular to the x–y plane (scale bar: 300 nm), while (d)–(f) are taken with the x–y plane tilted 45° (scale bar: 1 μm). With d = 300 nm, the lines of woodpile structure obtained by MPL cannot be separated. Therefore, the period is expanded to d = 700 nm (inset of (d) image) for MPL^[1].

Fig. 3. (Color online) The original 3D model and fabricated SEM morphology of Nezha (40 μm in height) using Pr1 and Pr2. Scale bar: 10 μm. The hair lines of Nezha made by Pr2 are more clearly visible than that made by Pr1, which demonstrates that MC-MPL has a better ability to fabricate fine structures than MPL^[1].