Fig. 1. Schematic diagram of preparing the Si₃N₄/WS₂/Al₂O₃ sandwich nanolaser array by PVD and ALD

Fig. 2. (a) Structural diagram of the Si₃N₄/WS₂/Al₂O₃ sandwich nanolaser; (b) Simplified model diagram for the simulation analysis

Fig. 3. (a) Fundamental TE radial mode and (b)-(c) high-order TE radial mode of the Si₃N₄/WS₂/Al₂O₃ sandwich nanolaser. Scale bar: 2 μm

Fig. 4. Variation of optical confinement factor of the Si₃N₄/WS₂/Al₂O₃ sandwich nanolaser with Al₂O₃ coating thickness T

Fig. 5. Side view of electric field distribution of the Si₃N₄/WS₂/Al₂O₃ sandwich nanolaser with different Al₂O₃ coating thickness. Scale bar: 300 nm

Fig. 6. Variation of optical confinement factor of the Si₃N₄/WS₂/Al₂O₃ sandwich nanolaser with Si₃N₄ microdisk diameter D

Fig. 7. Variation of optical confinement factor of the Si₃N₄/WS₂/Al₂O₃ sandwich nanolaser with Si₃N₄ microdisk thickness H

Fig. 8. Characterization results of devices after layered WS₂ was grown onto Si₃N₄ microdisks by the PVD method. (a)-(b) PL images of the device; SEM characterization results of WS₂ grown onto (c) microdisk array and (d) a single microdisk

Fig. 9. PL images of the Si₃N₄/WS₂/Al₂O₃ sandwich nanolasers below ((a), (c)) and above ((b), (d)) the lasing threshold