Fig. 1. Schematic diagram of (a) the proposed MWL chip; inset, the grating designed by the REC technique. (b) Microscopic top views of the proposed MWL ship with PEs and without PEs. (c) Scanning electron microscope (SEM) image of a detailed profile of the cross-section of a waveguide. π-EPS: equivalent π phase shift; P: sampling period; PE: power equalizer.

Fig. 2. (a) Spectrum and SMSRs of eight lasers working simultaneously at the same current are measured. (b) Eight-wavelength spectral fitting analysis. (c) Spectrum and SMSRs of the eight lasers after current tuning are measured. (d) Eight-wavelength spectral fitting analysis.

Fig. 3. (a) Spectrum and SMSRs of eight lasers operating simultaneously in a MWL chip with PEs are measured. (b) Eight-wavelength spectral fitting analysis.

Fig. 4. (a) Output power of the lasers varies with I_PE when the eight lasers are singly lasing. (b) Superposition spectra of the eight-channel DFB laser array under different PE bias currents.

Fig. 5. Superimposed optical spectra for I_Total in the range of 388–628 mA.

Fig. 6. (a) Wavelength shift of the MWL is analyzed when I_Total changes in the range of 388–628 mA with an interval of 48 mA. (b) SDOI and SMSRs for the MWL.

Fig. 7. Superimposed optical spectra for I_SOA in the range of 50–150 mA.

Fig. 8. (a) SDOI and SMSRs for the MWL when I_SOA changes in the range of 50–150 mA with an interval of 20 mA. (b) Output power of the MWL with I_SOA when the eight lasers are simultaneously lasing.

Fig. 9. RIN of each laser in the MWL chip when working alone.

Fig. 10. Eye diagrams of 25 Gb/s at eight wavelengths in the MWL chip.