Fig. 1. (a) X-ray diffraction spectrum of undoped PLZT, 1 mol% Er3+-doped, and 1 mol% Nd3+-doped PLZT ceramics; (b) the surface appearance photograph of undoped PLZT ceramics taken by an AFM; (c) the room temperature ground state absorption spectra; and (d) the transmittance spectra of undoped PLZT, 1 mol%–3 mol% Er3+-doped, and 1 mol% Nd3+-doped PLZT samples (the inset is the photograph of the undoped, Er3+-doped, and Nd3+-doped PLZT samples).

Fig. 2. (a) Schematic illustration of the experimental setup of the photochromic effect; (b) the dynamic change of the transmittance of light in the darkening, self-bleaching, and infrared bleaching processes; (c) the trapping and detrapping process of electrons in TDT; (d) extinction coefficient and (e) refractive index change after UV light exposure; (f) the two-dimensional pseudo color distribution of the transmittance of light at different wavelengths in undoped PLZT ceramics (the inserted green line is the absorption spectrum of undoped PLZT ceramics).

Fig. 3. Two-dimensional pseudo color distribution of the transmittance of light at different wavelengths in (a) the 1 mol% Nd3+ ion-doped PLZT ceramics and (b)–(d) the 1 mol%–3 mol% Er3+ ion-doped PLZT ceramics.

Fig. 4. (a) Upconversion spectra of 1 mol% Er3+-doped PLZT ceramics excited by the laser at 980 nm after being irradiated by UV light at 365 nm with a power of 0 mW, 0.1 mW, and 0.12 mW for 1 min each (the inset is the schematic setup to measure the photoluminescence spectrum); (b) photoluminescence at 1550 nm of 1 mol% Er3+-doped PLZT excited by the laser at 980 nm after being irradiated by UV light at 365 nm with a power of 0 mW, 0.1 mW, and 0.12 mW for 1 min each.