Fig. 1. Recent representative research advances for the VLLC systems.

Fig. 2. Schematic diagrams of (a) the DPC and (b) the DPD. Insets: (i) principle of the DPC, (ii) the frequency spectra comparison, and (iii) the time-domain waveforms.

Fig. 3. Experimental setup of the 50-channel WDM VLLC system.

Fig. 4. Optical spectra of the 50 lasers.

Fig. 5. AIR versus bias current and signal Vpp for three typical wavelengths: (a) red, (b) blue, and (c) green.

Fig. 6. AIR comparison versus bias current for three typical wavelengths: (a) red, (b) blue, and (c) green. Insets: received constellations for red (i) with (w) and (ii) without (w/o) DPC, for blue (iii) w and (iv) w/o DPC, and for green (v) w and (vi) w/o DPC.

Fig. 7. Estimated channel frequency response comparison for three typical wavelengths: (a) red, (b) blue, and (c) green.

Fig. 8. Bit allocation of three typical wavelengths: (a) red, (b) blue, and (c) green.

Fig. 9. Data rates and BER of the 50 VLLC channels.