Simon Arega Gebrewold

Reflective-SOA Fiber Cavity Laser as Directly Modulated WDM-PON Colorless Transmitter

Reflective semiconductor optical amplifier (RSOA) fiber cavity lasers are attractive colorless, self-seeded, self-tuning, and directly modulatable sources for passive optical networks (PONs). They comprise of an RSOA in the optical network unit as the active element, a distribution fiber as the laser cavity, a waveguide grating router, and a common reflective mirror with the latter two positioned at the remote node. In this paper, we introduce a model and perform simulations to elucidate the recently discovered successful operation of this new PON source. The results are in agreement with experiments; the formation of a narrow laser spectrum with a relatively constant output power is seen despite a relatively broad passband window of the waveguide grating router. We further study mode competition and mode partition noise. It is shown that proper chromatic dispersion management can overcome mode partition noise limitations. The quality of the RSOA fiber cavity laser does not degrade when being directly modulated and as a result these highly multimode lasers offer an economic way to transport Gbit/s upstream data over kilometers of fiber in a wavelength division multiplexing-PON.

Continuously tunable true-time delays with ultra-low settling time

Ultra-fast, continuously tunable true-time delays are key components in many microwave and optical communications subsystems. In this paper, we introduce and demonstrate a new implementation method of a continuously tunable true-time delay featuring a settling time in the order of tens of picoseconds. Our solution relies on the splitting and combining of complementary phased shifted spectra (CPSS). It works for large bandwidth signals, has a low complexity, offers moderate losses, and can be fully integrated.

Self-tuning transmitter for fibre-to-the-antenna PON networks

WDM PONs offering point-to-point connectivity, independence of multiple access protocol to share the medium are good candidates for supporting the new fronthaul fibre network requirements. The necessity to allow inventory and maintenance cost reduction will favour WDM PON solutions based on colourless transceivers. We present the proposal of a network embedded self-tuning colourless transmitter, based on reflective semiconductor optical amplifier (RSOA) self-seeding architectures. We analyse the fibre-to-the-antenna network requirements and evidence the capabilities of the network embedded self-tuning colourless transmitter, showing its principle of operation, the development and the modelling of the active elements. We present and discuss recent experimental results up to 10Gbit/s, which are encouraging for the transmitter exploitation in fronthaul WDM multiplexing technology.

Self-seeded RSOAs WDM PON field trial for business and mobile fronthaul applications

GEth, CPRI and 10 Gbit/s transmissions are experimented using amplified and standard self-seeded RSOA WDM PON systems. A field trial setup was exploited to test the system performance in terms of reach and optical budget.

Ultra-fast tunable true-time delay using complementary phase-shifted spectra (CPSS)

We introduce an ultra-fast, continuously tunable true-time delay, featuring settling times of tens of picoseconds. Our solution operates for large bandwidth signals, has a low complexity, low losses, and can be fully integrated.

Ultra-Fast Millimeter Wave Beam Steering

In this paper, we demonstrate ultra-fast millimeter wave beam steering with settling times below 50 ps. A phased array antenna with two elements is employed to realize beam steering. The phased array feeder is implemented with a recently introduced time delay line that provides, at the same time, an ultra-fast tunability, broadband operation, and continuous tuning. Our implementation is used to perform symbol-by-symbol steering. In our demonstration, the beam direction is switched between two sequentially transmitted symbols toward two receivers placed 30° apart. We show the successful symbol-by-symbol steering for data streams as fast as 10 GBd. The suggested scheme shows that the ultra-fast beam steering is becoming practical and might ultimately enable novel high bit-rate multiple access schemes.

Demystification of self-seeded WDM access

The operating principles of a self-seeded cavity are explained, and its main characteristics are described. Some practical implementation cases are also discussed.

Plasmonic phased array feeder enabling symbol-by-symbol mm-wave beam steering at 60 GHz

We demonstrate an on-chip 60 GHz phased array antenna feeder with record-low footprint (active area <;2.5μm2), based on ultra-compact plasmonic modulators. The chip footprint is only limited by the contact pads size. Our implementation also enables ultra-fast steering with less than 1 ns reconfiguration time.

Time-space division multiplexing enabled by ultra-fast beam steering

We demonstrate a microwave photonic phased array antenna concept capable of symbol-by-symbol steering at symbol rates of 10 GBd. Such a system may increase mobile network capacity and reach by spatially addressing individual users.

WDM PON RSOA-based self-tuning transmitters: An insight from the EU FP7 ERMES project

We present the final results of the EU FP7 ERMES project, which focused on the development of a WDM-PON colourless self-tuning transmitter based on RSOA self-seeding. Measurements obtained with a packaged O-band RSOA in a SFP+ compatible transmitter are reported at 1.25, 2.5 and 10 Gb/s for various drop fibre lengths, up to 6.3 km and 1 km respectively. We successfully demonstrated transmission over more than 20-km SSMF with bit error rates below the FEC limit (3·10-3). The transmission length is limited only by the power budget while the chromatic dispersion has no impact, even at 10 Gb/s. Finally, we give an overview of the BER field trail measures performed with the 18-km fibre loops over the city of Lannion (France). We tested the ERMES transmitter at 2.5 Gb/s and 10 Gb/s with various PRBS lengths to prepare GEth and CPRI tests. Field trial results resembled laboratory tests, successfully obtaining transmission over up to 2 fibre loops.