Low cost coherent receivers for UD-WDM NRZ systems in access networks

Abstract

This paper presents the first experimental achievements of the COCONUT project which aims at demonstrating ultra-dense Wavelength Division Multiplexing Passive Optical Networks (udWDM-PON) by means of low-cost coherent solutions. COCONUT should exploit low-cost optical components and simple electronics so that the cost of typical line terminals would be affordable to the end-users. Among different technical approaches considered within the project; we focus here on the solutions based on simple OOK-NRZ format. We developed an original improvement of the conventional phase-diversity coherent detection schemes providing for polarization independent operations without doubling the receiver structure. As a result we demonstrated that passive networks of high-power budget (> 45 dB i.e. up to 60 km reach and more than 64-way power splitting) are feasible over a 6.25 GHz grid by using a limited number of photodiodes a simplified analog processing and free-running DFBs

Hybrid Wavelength Switched-TDMA High Port Count All-Optical Data Centre Switch

“…DSP to recover data from full coherent transmission is estimated to use 20W of the 32W available in CFP format transceivers [14]; this DSP-free receiver could therefore operate with at most 37.5% of the power consumption of a comparable fully coherent device. A simplified receiver [15] could be used to provide similar levels of performance, but either at the loss of polarisation diversity or a power budget penalty due to optical component losses, constraining the construction of the fibre network core.…”

1.25–3.125 Gb/s per user PON with RSOA as phase modulator for statistical wavelength ONU

“…Coherent detection has been confirmed that it can improve the sensitivity and the spectrum efficiency in access network [12,13]. Compared with homodyne detection, heterodyne detection presents inherent image frequency interference, and as a result homodyne/intradyne reception is considered a better solution [14].…”