Experimental demonstration of 25-Gb/s downstream transmission using 10-Gbps optics for next-generation PONs

In this paper, we experimentally demonstrate a cost-effective 25-Gb/s downstream transmission of PON based on electro-absorption modulated laser (EML) and directly modulated laser (DML) both operating at 7-GHz. A 10-Gbps class avalanche photodiode (APD) is employed at the receiver. Adaptive feedforward equalizer (FFE) cooperating with faster-than-Nyquist NRZ (FTN-NRZ) technique, which includes FTN precoder and post decoder, are adopted to process the bandwidth limited signal. The experimental results indicate that pre-emphasis has a gain of 0.5 dB in EML based optical back-to-back transmission, and for 20-km standard single mode fiber (SSMF) link, the receiver sensitivities of -28.4 dBm and -26.5 dBm are achieved for EML and DML, respectively. According to the experimental results, the FTN-NRZ technique shows its superiority in receiver sensitivity, which is an alternative of cost-effective solution for future 100Gb/s TWDM-PON.