RSOA-based self-seeded transmitters: The ERMES project results and offsprings

The EU FP7 ERMES project focused on the development of a wavelength division multiplexed passive optical network (WDM PON) colourless self-tuning transmitter based on reflective semiconductor optical amplifiers (RSOAs) self-seeding. These transmitters represent low cost solutions to achieve self-organized wavelength access networks. The EU ERMES project developed self-tuning transmitters both in the C- and O- band with tens of kilometres reach up to 10 Gb/s. During the project we developed different self-seeding architectures with single RSOA exploitation (standard self-seeding) or two-RSOA exploitation (amplified or face-to-face self-seeding). The employment of Faraday rotators and mirrors in retracing configurations ensured polarization insensitive operation of the self-seeded architectures allowing for the exploitation of high gain C and O-band RSOAs, which present a very high polarization dependent gain. The project evaluated the coexistence of time division multiplexing (TDM) and WDM PON supporting high-numbers of users: although the burst mode operation was limited by the build-up time of the long-cavity laser, the rise time is compatible with a sleep mode for energy saving. After the project conclusion self-seeded transmitters have been exploited with alternative modulation formats including polarization division multiplexing and frequency division multiplexing in order to increase the achievable bit rates. Finally further studies to increase modulation cancellation inside self-seeded transmitters have been performed.