Fig. 1. The 3D schematic of VCSEL structure

Fig. 2. Reflective spectra of 22-pair DBR consisted of GaAs and AlAs materials

Fig. 3. The Gain spectra of active region andcavity mode changing with operation temperatures，and thered solid circle indicated the cavity-mode gain at different temperatures^［33］

Fig. 4. The Quantum precision measurement devices^{［35，42-43］}

Fig. 5. The physical components of chip scale atomic clock^［21］

Fig. 6. The external-cavity VCSEL operated under high temperatures and its linewidth^［52］

Fig. 7. The VCSEL integrated with grating structure，which is used to control the mode and polarization of VCSEL，reported by ULM university^［56］

Fig. 8. The inter-contact VCSEL structure reported by Ioffe institute and its diamond-shape oxide aperture^［38］

Fig. 9. Theelliptical surface shallow integrated on the VCSEL surface，reported by CIOMP（Changchun Institute of Optics，Fine Mechanics and Physics）^［66］

Fig. 10. The schematic diagram of VCSEL reported by CIOMP，emitting high single-mode power^［69］

Fig. 11. The VCSEL mesa with closeisolation trench，reported by Suzhou Institute of Nano-Tech and Nano-Bionics^［71］

Fig. 12. The schematic structure of an oxide-confined VCSEL incorporating a built-inindex guide，reported by Institute of Semiconductors^［74］

Fig. 13. Proportion of energy consumption in data center

Fig. 14. The schematic structure of high-speed 980 nm VCSEL used for the optical inter-connections^［82］

Fig. 15. Schematic diagram and top view of VCSELs with different Zn diffusion diameters^［86］

Fig. 16. The integrated high-speed VCSEL module reported by IMB and CUT^［90］

Fig. 17. Schematicdiagram of VCSELs with Zn diffusion^［91］

Fig. 18. The SEM image of high-speed VCSELs^［92］