Study On Time And Wavelength Division Multiplexed Passive Optical Network

In 2011, full-Service Access Network union introduced Next-Generation Passive Optical Network (NG-PON2), which solves problems, such as growth of Internet traffic and the cost of investments. In 2012, after one year discussions and experiments with different architectures, Time and Wavelength Division Multiplexing(TWDM) approach was selected as a primary solution for the implementation of NG-PON2. TWDM technology is a hybrid of Time Division Multiplexing (TDM) and Wavelength Division Multiplexing (WDM) with at least 40 Gb/s downstream and 10 Gb/s upstream bit rate. Besides of high capacity, TWDM-PON allows the opportunity to coexist with previous generations of PON that significantly decreases the cost of the network.Recently, there has been increasing interest in larger split extended-reach optically amplified schemes for future long reach PONs, which offer the potential to eliminate the costs of the electronic interface between the access and the outer core/metro backhaul network. However, some schemes have been limited to architectures where only TDM is used to share the network capacity between the customers.In this paper, we investigate an access network architecture that employs extended-reach optically amplified TWDM-PON to enable a number of such large-split long-reach PONs, to share the same amplifier plant and backhaul fiber.Semiconductor Optical Amplifier (SOA) is chosen to offer optical amplification due its large wavelength range and the potential for integration with the other optical components, enabling a longer reach and larger split optical access network.Furthermore, the proposed long-reach TWDM-PON system is evaluated by simulations created in VPIphotonics software. In the system, 3 wavelengths, 1×64 splitters are used, hence 192 optical network units (ONU) are connected to one optical line terminal (OLT). For each simulation, the bit error rate (BER) and injection current at semiconductor optical amplifier (SOA) were measured. Both burst Gaussian mode and classical Gaussian mode are used in the measurements. Different fiber lengths, receiver responsivity, noise figures, attenuations, optical dispersion and bit rates are discussed respectively in this paper. The results show the proposed system provides support for the 3×64 ONUs with downstream transmission of 2.5 Gb/s, allowing a maximum transmission length of 150 km under the BER criterion of 3.8×10-3.