Fig. 1. Structure of a VBG external cavity second harmonic generation semiconductor laser

Fig. 2. Power characteristics of semiconductor lasers during free emission

Fig. 3. Spectral characteristics of semiconductor lasers under free emission at different temperatures

Fig. 4. Spectral characteristics of semiconductor lasers under free emission at 28 ℃

Fig. 5. Far-field spot of semiconductor lasers at different temperatures and currents for free emission

Fig. 6. Power characteristics of second harmonic generation in the semiconductor lasers during free emission

Fig. 7. Spectral characteristics of second harmonic generation in the semiconductor laser under free emission at different temperatures

Fig. 8. Spectral characteristics of second harmonic generation in the semiconductor laser at 28 ℃ free emission

Fig. 9. Power characteristics of a VBG external cavity semiconductor laser with a diffraction bandwidth of 0.3 nm

Fig. 10. Spectral characteristics of a VBG external cavity semiconductor laser with a diffraction bandwidth of 0.3 nm at different temperatures

Fig. 11. Far-field spot of a VBG external cavity semiconductor laser with a reflection bandwidth of 0.3 nm at different temperatures and currents

Fig. 12. Power characteristics of second harmonic generation in a 0.3 nm diffraction bandwidth VBG external cavity semiconductor laser

Fig. 13. Spectral characteristics of second harmonic generation in a 0.3 nm VBG external cavity semiconductor laser at different temperatures

Fig. 14. Spectral characteristics of second harmonic generation in a 28 ℃ diffraction bandwidth of 0.3 nm VBG external cavity semiconductor laser

Fig. 15. Output characteristics of a VBG external cavity semiconductor laser with a diffraction bandwidth of 0.1 nm

Fig. 16. Spectral characteristics of a VBG external cavity semiconductor laser with a diffraction bandwidth of 0.1 nm at different temperatures

Fig. 17. Far-field spot of a VBG external cavity semiconductor laser with a reflection bandwidth of 0.1 nm at different temperatures and currents

Fig. 18. Power characteristics of second harmonic generation in a 0.1nm diffraction bandwidth VBG external cavity semiconductor laser

Fig. 19. Spectral characteristics of second harmonic generation in a 0.1 nm VBG external cavity semiconductor laser at different temperatures

Fig. 20. Spectral characteristics of second harmonic generation in a 28 ℃ diffraction bandwidth of 0.1 nm VBG external cavity semiconductor laser