Wavelength conversion towards Rayleigh backscattering tolerant PONs via four-wave mixing in SOA-based ONUs

Wavelength shifting in PONs with downstream signal remodulation is presented, allowing upstream transmission over trees with 25km feeder and 1:32 split with penalties <2dB, originally Rayleigh backscattering limited. Side-mode suppression is analyzed for hybrid PONs.Peer ReviewedPostprint (published version

Colorless FSK Demodulation and Detection With Integrated Fabry-Perot-Type SOA/REAM

A receiver for optical frequency modulated signals, based on colorless demodulation and detection, is presented. An integrated combination of semiconductor optical amplifier (SOA) and reflective electroabsorption modulator (REAM) is designed to obtain a comb-like spectral detection function, replacing the typically required costly frequency discrimination filter. The spectral properties of the designed SOA/REAM chip are discussed and the reception of a 10-Gb/s optical frequency modulated downstream signal is demonstrated, proving the applicability as receiving optical subsystem in the customer premises equipment of fiber-to-the-home access networks with wavelength reuse for upstream transmission and no downstream crosstalk.Peer ReviewedPostprint (published version

L-Band In-Line Remote Amplification for an Extended WDM/PON Ring Architecture

In this paper, a study on a fully passive WDM/PON ring architecture which reaches 19 km distance, while serving more than 1000 users with symmetric several hundred Mbit/s per user is presented. The design is based on SARDANA (Scalable Advanced Ring -based Passive Dense Access Network Architecture) and was generated as an alternative solution, with its novelty laying on the use of L-band in line remote amplification. The simulation of an extended access WDM/TDM PON formed in a double fibre ring with single fiber trees was created. The network’s operation has been tested for several conditions of usage (i.e. maximum number of users,transmission power and pump power) and an optimization of the design has been performed. The target was to achieve, with given transmission and pump power, the reach of more then 1000 users with input power high enough to permit the use of an RSOA at the ONU. The use of L-band signals and special doped fiber has permitted the effective use of RSOAs in the total of the end users.Peer ReviewedPostprint (published version

Fortistis: Split extension in dense passive optical networks by inline amplification with remote ASE-shaped pump delivery via colorless optical network units

A method for extending the customer density via ASE-pumped splitters in the tree in a WDM/TDM-PON is presented. The influence of Rayleigh backscattering in the feeder is faced, originally prohibiting any upstream transmission.Peer ReviewedPostprint (published version

Enhancing dynamic student learning by teamwork in innovative projects at an Erasmus Mundus master subject adapted to the EHEA (EEES)

The EHEA (EEES in Spain) is creating common academic degree standards comparable and compatible between the European countries. The definition of the new Credit unit, the ECTS, focused on the hours of study devoted by the students, is also promoting the renovation of the educational process at the higher studies of Graduate Degree and Master. We describe the experience of innovation of the teaching practice of the “Fibres & Telecommunications” subject of the Master PhotonicsBCN (part of the Erasmus Mundus Master EUROPHOTONICS), by introducing team9 working techniques for promoting: the development of cooperative learning, interpersonal skills, and positive interdependence among the students, not forgetting the individual initiative and responsibility. The teamwork is oriented to small innovation projects (inspired in state9of9the9art research challenges faced by the European FP7 EURO9FOS Network9 of 9Excellence) promoting interactive and dynamic student learning process. Each team member is spontaneously encouraged to learn as much as possible on both: the area of his task inside the common project, and also the influence of his task in the over all results of the project. This is implemented by the use of commercial software for professional systems deployment (VPIphotonics TM ), which allows each team to check the real viability of their innovative solutionPostprint (published version

Random number generation by coherent detection of quantum phase noise

In 2010 Qi et al. [Opt. Lett. 35(3), 312 (2010)] demonstrated a random number generator based on the drift of the phase of a laser due to spontaneous emission, The out-of-the-lab implementation of this scheme presents two main drawbacks: it requires a long and highly unbalanced interferometer to generate a random phase with uniform probability distribution, or alternatively, a shorter and slightly unbalanced interferometer that notwithstanding requires active stabilization and does not generate a uniform probability distribution without randomness extraction. Here we demonstrate that making use of the random nature of the phase difference between two independent laser sources and two coherent detectors we can overcome these limitations. The two main advantages of the system demonstrated are: i) it generates a probability distribution of quantum origin which is intrinsically uniform and thus in principle needs no randomness extraction for obtaining a uniform distribution, and ii) the phase is measured with telecom equipment routinely used for high capacity coherent optical communications. The speed of random bit generation is determined by the photodetector bandwidth and the linewidth of the lasers. As a by-product of our method, we have obtained images of how phase noise develops with time in a laser. This provides a highly visual alternative way of measuring the coherence time of a laser.Peer ReviewedPostprint (published version

Demonstration of a full duplex PON featuring 2.5 Gbps Sub Carrier Multiplexing downstream and 1.25 Gbps upstream with colourless ONU and simple optics

We demonstrate a full-duplex DPSK SCM PON operating at 2.5Gbps/1.25Gbps bitrates, with RSOA ONU and simplified scheme. It achieves low sensitivity and is implemented with low-cost components.Peer ReviewedPostprint (published version

Optimization of Rayleigh-limited WDM-PONs with reflective ONU by MUX positioning and optimal ONU gain

In this work, the influence of the distribution element position and the reflective optical network unit (ONU) gain in wavelength-division-multiplexing passive optical networks are reported. After the theoretical and experimental analysis, it is determined that the best crosstalk-to-signal ratio is achieved if the multiplexer is placed either in the ONU or optical light termination vicinity, and the ONU gain has a new optimum value depending on the position. Also, it is demonstrated that Rayleigh backscattering is generally irrelevant in downstream transmission.Peer ReviewedPostprint (published version