Fig. 1. Diagram of typical optical spectrum of output from spectral beam combining (SBC)

Fig. 2. Two key parts of dense SBC

Fig. 3. System structure diagram of SBC with closed loop

Fig. 4. Schematic diagram of SBC system with hybrid of wavelength-lock and superposition^[9]

Fig. 5. Characteristics of SBC system with 11 laser diodes. (a) Output spectrum; (b) curve of output power versus input current^[12]

Fig. 6. System structure diagram of SBC with diverse of wavelength-lock and superposition

Fig. 7. Diagram of SBC system based on wavelength-lock with TFF and superposition with optical gratings^[42]

Fig. 8. Output characteristics of SBC with open loop using TFF^[45]. (a) Output power versus input current; (b) light spot distribution

Fig. 9. Two ways of CBC phase-lock ^[47]. (a) Active phase control; (b) phase-lock with external cavity

Fig. 10. Ways of CBC superposition^[47]. (a) Use of beam splitter; (b) use of phase grating

Fig. 11. Construction ways of external cavity^[47]. (a) Binary tree; (b) cascaded; (c) DOE

Fig. 12. CBC with conical amplification chip^[54]. (a) System structure diagram; (b) power distributions of different diffraction orders

Fig. 13. System structure of active phase control CBC based on MOPA technology with 900 laser diodes^[58]

Fig. 14. System structure of active phase control CBC based on conical amplification chip and MOPA technology with 4 laser diodes^[59]

Fig. 15. MOPA quasi-continuous CBC based on conical amplification chip^[64]. (a) System structure; (b) output characteristics