100 Gb/s (4 × 25 Gb/s) real-time coherent UDWDM-PON with a large power budget

We propose a 100-Gb/s coherent ultra-dense wavelength-division multiplexing passive optical network (UDWDM-PON) structure with a large power budget by placing an erbium-doped fiber amplifier at the optical line terminal side for amplification of optical signals in both the uplink and downlink. Then we experimentally demonstrate a real-time ${4} \times 25 \text- {\rm Gb/s}$4×25-Gb/s coherent UDWDM-PON at 12.5-GHz spacing over 50-km standard single-mode optical fiber. A high sampling rate analog-to-digital converter is designed for the 25-Gb/s real-time coherent optical module. Experimental results show that 100-Gb/s bidirectional transmission can be realized. The downlink power budget can be more than 44 dB, which can support more than 1000 users based on the proposed structure. The effects of several parameters have also been investigated in the experimental demonstration. The 24-h real-time performance evaluation for bidirectional transmission is conducted to prove the feasibility of real-time field-programmable gate array based transceivers in the proposed UDWDM-PON structure. An off-line experimental demonstration is also conducted to verify the feasibility of burst-mode operation in the uplink.