Fig. 1. Schematic diagram of polarization-maintaining dual-wavelength single-frequency fiber laser

Fig. 2. Spectrum of polarization-maintaining dual-wavelength single-frequency fiber laser

Fig. 3. Scanning interferometer image of dual-wavelength single-frequency fiber laser

Fig. 4. (a) Frequency spectrum diagram of the beating signal of the dual-wavelength single-frequency fiber laser; (b) Stability measurement of the center frequency and the intensity of the beating signal

Fig. 5. Schematic diagram of four-wave mixing principle

Fig. 6. Schematic diagram of multi-wavelength single-frequency fiber laser

Fig. 7. State test of laser operating. (a) Spectrum; (b) Scanning inter-ferometer image

Fig. 8. Output spectrum of multi-wavelength single-frequency laser. (a) Complete spectrum; (b) Partial spectrum analysis

Fig. 9. Autocorrelator image of the multi-wavelength single-frequency laser