Fig. 1. The evolution of standard PON in different stage

Fig. 2. The architecture of various PONs

Fig. 3. The hardware simplification scheme of simplified coherent transceiver

Fig. 4. The DSP simplification scheme of simplified coherent receiver

Fig. 5. Schemes of uplink burst mode detection

Fig. 6. Power adaptive adjusting scheme

Fig. 7. PON architecture and different ONU distributions

Fig. 8. Schemes for data rate adaptive adjustment

Fig. 9. Laser sharing upstream and downstream FBMC-PON

Fig. 10. scheme of SOA current adjusting flexible PON