Physical impairments on high aggregate data rate passive coherent optical networks

This paper addresses technical and standard challenges on very high aggregate wavelength-division multiplexing (WDM) based passive optical networks (PON) capable of delivering, up to 1000 wavelengths/users separated by a few Gigahertz broadband connections at 1-10Gb/s through a single optical fiber. These networks rely on employing high-order modulation formats such as M-ary PSK (phase-shift keying) or M-ary QAM (quadrature amplitude modulation) along with coherent detection to provide high receiver sensitivity and wavelength selectivity. The first part of the paper focus on the most relevant standard challenges as to comply with the already populated wavelength spectrum by technologies such as Video overlay, Gigabit, Ethernet, 10GEthernet PONs. The second part of the paper deals with technical challenges as to assess the overall system performance and identify the limits provided by UDWDM (ultra-dense wavelength-division multiplexing) technologies. This study includes splitting ratio versus multiplexing / demultiplexing requirements as well as the evaluation of the most relevant transmission physical impairments such as fiber nonlinearities.