Fig. 1. Schematic diagram and operation principle of multi-wavelength RFL.

Fig. 2. (a) Filtered spectrum of AOTF at the central wavelength of 1123.0 nm. (b) Power evolution under different pump powers at the central wavelength of 1123 nm. Output spectrum of 1123 nm lasing at pump power levels of (c) 8.45 W and (d) 8.84 W.

Fig. 3. (a) Output spectra at different central wavelengths and corresponding maximum output power. (b) Spontaneous Raman lasing appears while the central wavelengths are 1114.4 and 1132.5 nm.

Fig. 4. Spectrum of dual-wavelength output with the interval of (a) 10 nm and (b) 4 nm.

Fig. 5. (a) Filtered spectrum with dual-channel RF signal. Output spectra with FWHM of (b) 4 nm and (c) 4.5 nm.

Fig. 6. (a) Spectra of tri-wavelength and five-wavelength output with equal/similar amplitude. (b) Corresponding filtered spectra.

Fig. 7. Five-wavelength output with customized shape.