26-Gbps PON Transmission over 40-km using Duobinary Detection with a Low Cost 7-GH-z APD-Based Receiver

26-Gbps serial transmission over 40-km is demonstrated for downstream PON. Duobinary detection allows for a 7-GHz APD receiver at the ONU. Transmission at this rate enables future 100G-EPON in a cost effective way using 4x25.8-Gbps TWDM. Introduction Time Division Multiplexed Passive Optical Networks (TDM PON) beyond the state-of-theart 10-Gbps transmission are challenging because of chromatic dispersion (CD) and the need for higher optical power levels to meet signal to noise ratio requirements at the receiver. Most PON solutions for higher transmission capacities have therefore explored alternative schemes such as Time and Wavelength Division Multiplexing (TWDM), Orthogonal Frequency Division Multiplexing 1-4 (OFDM), or ultra-dense WDM . In the present paper, we demonstrate a cost effective solution to scale PON capacities by extending the serial TDM downstream rate to 26-Gbps. Conventional Non Return to Zero (NRZ) detection at this rate requires a receiver bandwidth of at least 20-GHz, which is currently not commercially available using Avalanche Photo Detector (APD) technology. Using a P-type / Intrinsic / N-type (PIN) detector based receiver would require a Semiconductor Optical Amplifier (SOA) as a pre-amplifier at each Optical Network Unit (ONU) to meet the optical budget requirements, which stands against the stringent cost requirements in an access network. By using NRZ transmission in combination with electrical duobinary detection for 26-Gbps PON, we reduce the required receiver bandwidth from 20-GHz to 7-GHz.