Fig. 1. Multimodal luminescence mechanism based on electron-hole model. (a)‒(c) Multimodal trap filling processes; (d) various forms of energy induced trap emptying and multimodal luminescence processes;(e) schematic of up-conversion persistent luminescence in Zn₃Ga₂GeO₈∶1%Cr³⁺, 5%Yb³⁺, 0.5%Er³⁺ system^[16];(f) schematic of up-conversion-like trapping process in CaSnO₃∶Bi²⁺ system^[17]

Fig. 2. Thermo-, photo-, and mechano-responsive multimodal luminescence in UV-irradiated La_1.95Ti₂O₇∶Pr³⁺ as well as its application shows^[1]. (a) Thermo-luminescence spectra of sample treated under different temperatures; (b) thermo-luminescence spectra of sample irradiated by near-infrared lasers with different power densities; (c) thermo-luminescence spectra of sample exerted by different pressure loads; (d) stimulus-responsive shows under multimodal excitation resources

Fig. 3. Exploring examples of optical information storage applications. (a) Thermo-luminescence spectra of LiGa₅O₈∶Mn²⁺ glass treated under different temperatures^[22];(b) 3D optical readout of images encoded in different layers with heat aid at 150 ℃^[22]; (c) schematic of multilevel optical data storage and readout from multimodal luminescent phosphor (Ba₂SiO₄∶0.005Eu²⁺, 0.001Tm³⁺, 0.001Ho³⁺, 0.0005Dy³⁺) film ^[18];(d) X-ray imaging technique of bent objects^[23]

Fig. 4. Exploring examples of optical anti-counterfeiting and information encryption applications. (a) Taiji image examples made by BaGa₂Si₂O₈∶Eu²⁺, Eu³⁺, Pr³⁺ as well as their application of multimodal luminescence in anti-counterfeiting^[2]; (b) illustration of real time multidimensional anti-counterfeiting based on Mn-doped (Na/Li)₂(Zn/Mg)(Si/Ge)O₄ material^[28]; (c) luminous stability of leaf-shaped composite film against water immersion^[28]

Fig. 5. Exploring examples of sensing and labeling applications. (a) Schematic of visualizing quasi-dynamic crack propagation using SrAl₂O₄∶Eu²⁺/Dy^3+[34]; (b) application of stress induced carrier storage in vehicle collision monitoring^[35]; (c) mechano-luminescence spectra of SrZnSO∶0.02Tb³⁺,0.01Eu³⁺ at various temperatures and I_Tb/I_Eu versus temperature, with CIE chromaticity coordinates of mechano-luminescence shown in inset^[36]; (d) up-conversion persistent luminescence of Lu₂Pr_0.01Gd_0.99Al₂Ga₃O₁₂ ceramic chips stimulated by blue LED in bright environment^[37]; (e) ultraviolet-C (UVC) radiation images of Ca₂Al₂SiO₇∶Pr³⁺ ceramic chips placed in tree trunks in direct sunlight^[38]