Fig. 1. Schematic of the experimental setup

Fig. 2. Power-current curve of the free-running WRC-FPLD and optical spectrum of WRC-FPLD biased at 52.00 mA

Fig. 3. Optical spectra，power spectra，and time series of a WRC-FPLD under current modulation with f_m=1.6 GHz and P_m=0，0 dBm，and 19 dBm

Fig. 4. Optical spectra output from the gain-switched WRC-FPLD subject to single optical injection with P_inj=3.397 µW and different λ_inj

Fig. 5. Evolutions of number of comb lines and carrier to noise ration with the injection light wavelength under P_inj=3.397 µW，and with the injection light power under λ_inj=1 545.319 2 nm

Fig. 6. Optical spectra output from the optical injected gain-switched WRC-FPLD after introducing an extra optical injection with P_inj2=4.3 µW and different λ_inj2

Fig. 7. For Single Optical Injection（SOI）and Dual Optical Injection（DOI）（first row），and for dual optical injection that the two central wavelengths are relatively far（Case1）and close（Case2）（second row），the power spectrum of OFC generated by the gain-switched WRC-FPLD，spectral distribution of the fundamental signal centered at 1.6 GHz，and Single Sideband（SSB）phase noise of the fundamental signal