Edson Moschim

Optical amplitude multiplexing through four-wave mixing in optical fibers

We propose a new optical amplitude multiplexing technique that consists of merging two wavelength multiplexed on-off keying (OOK) signals into a single quaternary amplitude shift keying signal. This technique is based on four-wave mixing in a single-mode optical fiber and requires power offset from the OOK signals. Simulation results indicate that the multiplexing may be performed between signals of the same or different bit rates. As a consequence, the proposed technique may be used not only for increasing spectral efficiency but also for optical labeling.

Quaternary optical packets generated by fiber four-wave mixing

Recent work suggests that fiber four-wave mixing may be used to merge two wavelength multiplexed binary channels into a single quaternary signal. In this letter, we investigate the application of this technique to the optical packets generation considering that a 10-Gb/s payload is optically multiplexed to a 2.5-Gb/s label. Computer simulations are used to analyze the propagation of the generated quaternary optical packet in the dominance of amplified spontaneous emission noise. Results suggest that the optical packet may be propagated through metropolitan area networks length scales and that an average power around 0 dBm should be used to minimize the packet bit-error rate.

Impact of PMD on hybrid WDM/OCDM networks

In this work, we investigated the impact of polarization-mode dispersion (PMD) in optical networks using the hybrid technology of wavelength-division multiplexing and optical code-division multiplexing. In these networks, virtual paths based on code/wavelength channels (VCP/VWP) are dynamically established to attend the traffic demand. We use a routing channel assignment based on genetic algorithm to establish the VCP/VWPs. The main results show that the network blocking probability caused by PMD depends on parameters of optical orthogonal codes like weight and length.

The effects of polarization mode dispersion on 2D wavelength-hopping time spreading code routed networks

In this study, we investigate the effects of multiple access interference (MAI) and polarization mode dispersion (PMD) in 2D wavelength-hopping time spreading optical code paths. The main results show the MAI effects and PMD constraint at the outage probability. The contribution of these sources of interference is analysed to choose the better design of code parameters in order to increase the performance of networks based on optical code paths. These results could be applied to determine the parameters design in code/wavelength routed networks.

Analysis of electronic buffers in optical packet/burst switched mesh networks

We present in this paper the study of electronic buffering in an innovative architecture for optical packet/burst switched network (OPSN). This architecture comprises optical bufferless nodes with electronic packet queuing out of the optical layer, deflection routing to perform contention resolution and fully connected mesh topologies under uniform traffic distribution. We demonstrate, by means of simulation, that the studied architecture has a great improvement in performance when we introduce such electronic buffers, which are more efficient when used with the optimized mesh topologies.

Fibre optic sensor for diesel engine smoke measurement

A portable fibre optic sensor for diesel smoke measurements is described. The sensor works by sampling the smoke on the surface of a gluing white tape and measuring the diffuse reflectance from the stained tape. The precision of the detector system was 0.2%. The sensor values of diesel smoke (Rs) were compared with the results obtained using a Bosch smokemeter (Bn). A plot of Rs against Bn yielded a straight line with correlation coefficient of 0.983. Values of Rs were also expressed as a function of diesel smoke concentration. The sensor can perform continuous and remote measurements. It is of simple construction and operation and is particularly useful for on-road measurements.

Design of multi-rate optical code paths considering polarisation mode dispersion limitations

The authors propose an original design based on multi-rate optical code paths (OCPs) for transport in advanced wavelength-division multiplexing/optical code division multiplexing (WDM/OCDM) networks. The authors utilise multi-length optical orthogonal codes (OOC) to obtain multi-rate OCPs. The performance of the proposed scheme is analysed and the impact of multiple access interference (MAI) and polarisation mode dispersion (PMD) over these OCPs is evaluated. Results show that not only multi-rate operation can be achieved but also MAI effects can be reduced, while mitigating PMD effects.

Performance comparison of hybrid 1-D WDM/OCDMA and 2-D OCDMA towards future access network migration scenario

In this paper, we provide a performance comparison and analysis between a hybrid 1-D WDM/OCDMA system and a 2-D WHTS OCDMA system. In the hybrid system, OOC is employed as users code sequence of the OCDMA dimension. The simulation results show that the hybrid system presents better performance than the 2-D WHTS OCDMA system, and show also that under a standard BER scenario, i.e., BER = 10-9, the hybrid system can support at least 75% more simultaneous users than the 2-D OCDMA system for the analyzed case study. The analysis suggests that the hybrid 1-D WDM/OCDMA system is a qualified migration scenario since it can provide a smooth migration path from current networks towards OCDMA networks.

Evaluation of throughput and protection in optically switched metropolitan network architectures

In this study, we investigate the performance of optical packet/burst switched (OPS/OBS) architectures connected as mesh and as ring topologies for future optical metropolitan networks. Network throughput and protection to link failure under uniform traffic distribution for all nodes are investigated to evaluate the sensitivity of OPS/OBSN performance. Our data are based on analytic results and computer simulations that include a comparison between various mesh and ring topologies. We also consider detailed traffic distributions over the network links and the impact caused by failure of more or less loaded links, thus providing a method to select links that require protection, which can be very useful in network planning.

Performance analysis of optical code switching router

In this work we study and evaluate the performance of an optical code switching router (OCSR), intended to be utilised in hybrid wavelength-division multiplexing/optical code-division multiplexing (WDM/OCDM) networks. This OCSR can transport and route efficiently user data over optical code paths without departing from the optical domain. Limitations of the proposed OCSR are investigated and its superior performance demonstrated based on non-coherent prime codes. Our results indicate that our solution is useful in showing the effects of the optimum threshold level on the OCSR performance. We propose a continuous adjustment of the optimum threshold level based on the measurement of the mean optical power before the decoder. The influence of various parameters of the optical codes on the OCSR performance are also considered and evaluated. Copyright