Fig. 1. (a) Structure and concentration distribution of erbium doped by ion implantation^[27]; (b) Structure and concentration distribution of ytterbium doped by ion implantation^[28]; (c) Schematic diagram of Er-YSO bonding doping structure^[30]; (d) Schematic diagram of thulium doped structure^[26]

Fig. 2. Schematic diagram of preparation of Er-LNOI wafer by "smart cut" technology

Fig. 3. (a) Schematic diagram of Er-LNOI microdisk cavity prepared by femtosecond laser photolithography assisted chemo-mechanical etching technique;(b) Relationship between the emitted laser power and the 976 nm pump power^[34]

Fig. 4. (a)-(c) Observed laser signal and linewidth with the 974 nm pump; (d) Relationship between the emitted laser power and the 974 nm pump power (Inset: the observed green up-conversion fluorescence); (e)-(g) Observed laser signal and linewidth with the 1 460 nm pump; (h) Relationship between the emitted laser power and the 1 460 nm pump power (Inset: the observed green up-conversion fluorescence)^[35]

Fig. 5. (a) Spectrum evolution of the signal mode at different pump power; (b) Relationship between the signal power and the pump power^[36]

Fig. 6. (a) Schematic diagram of the preparation process of the Er-LNOI micro-ring cavity and waveguide coupling structure; (b)-(d) Scanning electron microscope image of the coupling structure of microring and waveguide^[37]

Fig. 7. (a) Collected signal spectrum in the range of 1 531.50-1 532.65 nm at 46.4 μW pump power; (b) Multi-peak lasing signal observed at a pump power of ~1 mW (Inset: the observed green up-conversion fluorescence); (c) Power and (d) linewidth of the signal mode under different pump powers^[37]

Fig. 7. [in Chinese]

Fig. 8. (a) Spectral evolution of the Er-LNOI racetrack microring resonator with increasing input pump powers; (b) Relationship between the emitted laser output power and the input pump power; (c) Laser signal wavelength by varying the electric voltage between −300 V and +300 V^[38]

Fig. 8. [in Chinese]

Fig. 9. (a) Increasing single-mode lasing signal with increasing pump power; (b) Spectrum of pump laser (Inset: optical micrograph of coupled microdisks with pump laser); (c) Relationship between signal output power and pump power (Inset: optical micrograph of coupled microdisks when lasing)^[40]

Fig. 10. (a) Single mode emission of Er-LNOI optical molecules in the range of 1500-1560 nm under different pump powers; (b) Output power and mode linewidth of single-mode laser at different pump powers; (c) Observed high side-mode suppression ratio signal (~26.3 dB) at a pump power of 900 μW (Inset: the observed green up conversion fluorescence)^[41]

Fig. 11. (a)-(b) Schematic diagram of Er-LNOI dual cavity structure and vernier effect^[42]; (c) SEM of prepared Er-LNOI single microring cavity; (d) Mode field distribution of the first four modes supported in microring cavity waveguide^[43]

Fig. 12. (a) Spectra of the output power of the Er-LNOI single mode laser at different pump powers; (b) Optical micrograph of the square lasing modes at 1 546 nm wavelength (Inset: the optical micrographs of the square modes of the up-conversion fluorescence around 550 nm wavelength (Left) and the pump light (Right)）^[44]

Table 1. Comparison of performance parameters of the reported LNOI microcavity lasers