fig9

Figure 9. (A) Temperature-dependent UC emission spectra of LiNbO₃-1050 sample at 300-660 K under 980 nm excitation^[117]. Reproduced from Ref.^[117] with permission from the Royal Society of Chemistry; (B) Schematic of the experimental setups for ion irradiation and ML measurement^[116]; (C) ML property of a Kr⁺-irradiated LiNbO₃ single crystal under three loading/unloading cycles^[116]; Reproduced from Ref.^[116] with permission from the American Chemical Society; (D) Photographs of Li_0.5Na_0.5NbO₃:Pr³⁺ pellet before loading and under compressive stress^[47]. Reproduced from Ref.^[47] with permission from the John Wiley and Sons; (E) Visible fluorescence spectra of VTE 0-5 h samples measured at 30 ℃^[119]; (F) The room-temperature upconversion fluorescence spectra from LiNbO₃:Er³⁺ on-chip ridge waveguides^[119]. Reproduced from Ref.^[119] with permission from the Elsevier; (G) Optical characterization of Er-doped LNOI ridge waveguides, including a microscopic image of the waveguide facet, green upconversion emission under 980 nm excitation, and experimental and simulated mode profiles at 1,550 nm^[120]. Reproduced from Ref.^[120] with permission from the Elsevier. LiNbO₃: Lithium niobate; Pr: praseodymium; VTE: vapor transport equilibration; ML: mechanoluminescence; Er: Erbium; LNOI: lithium-niobate-on-insulator.