Fig. 1. Schematic illustrations of GaN-based VCSELs with three different configurations. (a) Fully epitaxial DBR^[13]; (b) hybrid epitaxial/dielectric DBR^[9]; (c) double dielectric DBR^[19]

Fig. 2. Three typical structures of GaN-based VCSEL^[94]. (a) Hybrid DBR structure with epitaxial nitride bottom DBR (structure A); (b) double dielectric DBR structure (structure B) fabricated by substrate transfer technique; (c) double dielectric DBR structure (structure C) fabricated by ELO technique

Fig. 3. Heat flux distributions in GaN VCSEL with different structures^[94]. (a) Structure A with AlN/GaN DBR; (b) structure A with AlInN/GaN DBR; (c) structure B; (d) structure C

Fig. 4. Blue VCSEL array^[41]. (a) Schematic of blue VCSEL array; (b) emission image of blue VCSEL array operating at below threshold

Fig. 5. Room-temperature CW lasing characteristic^[54]. (a) Spectra of sample with a cavity length of 3041 nm at different currents; (b) spectra of sample with a cavity length of 2910 nm at different currents; (c) spectra of sample with a cavity length of 2652 nm at different currents. Inset: linewidth of the laising peak measured with a higher resolution

Fig. 6. Laser emission spectra at various injection currents measured at room temperature^[55]

Fig. 7. EL spectra of the VCSEL measured at different currents(inset: linewidth of the laising peak measured with a higher resolution)^[102-103]

Fig. 8. Emission spectra of the microcavity at room temperature^[109]