Hitless wavelength assignment in filterless optical access networks

Advantages offered by coherent detection systems in access networks are not limited to the increase of power budget due to the superior sensitivity. Channel selectivity is another intriguing feature offered by coherent systems that can be exploited to enable advanced system and network functionalities for access systems. Among them, we focus here on the implementation of filterless optical networks and network reconfiguration capabilities which might be required to satisfy dynamic load balancing requests and new terminal activations. We show that in the access domain these functionalities do not require DSP-aided coherent receivers, but can be easily realized by means of simpler, fully analogue real-time coherent terminals matching the access network low-cost paradigm. This paper discusses these concepts and how they can be experimentally implemented by using a novel wavelength allocation algorithm and real-time analogue coherent transceivers based on DFB lasers, whose wavelengths are tuned by a simple temperature control.