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- Transience analysis of bursty traffic with erbium doped fiber amplifiersPublication . Reis, Cláudia; Neto, Berta; Dionísio, Rogério Pais; Incerti, G.I.; Tosi-Beleffi, G.; Forin, D.; Teixeira, António; Rocha, A.M.; André, P.S.In this paper, we investigate experimentally the impact of optical amplifiers, namely Erbium Doped Fiber Amplifiers (EDFA) on Optical Burst Switching (OBS) networks, operating at 2.5 Gb/s (typical bit rate for current passive optical networks - PON). Bursts with 212 – 1 and 216 – 1 pseudo random binary sequence (PRBS) were studied, with different idle times. The use of traffic with variable idle time was assessed in order to evaluate the effect on the burst initial amplitude. We also analyzed the performance of the packet based system by measuring the Q factor at the receiver and concluded that the performance is not affected by the type of traffic (variable or fixed idle times).
- Experimental study of a phase modulator using an active interferometric devicePublication . Dionísio, Rogério Pais; Reis, Cláudia; André, P.S.; Nogueira, Rogério; Teixeira, AntónioA novel architecture for an optical phase modulator is presented and experimentally demonstrated. This approach relies on a commercially available integrated Mach- Zehnder interferometer structure with Semiconductor Optical Amplifiers (MZI-SOA) and it is based in cross-phase modulation effect (XPM). The feasibility of the proposed optical phase modulator is experimentally investigated using different scenarios of input power and bit rates.
- Comparative analysis of hybrid in line EDFA/Raman with simple raman amplification in WDM ring PON for C+L bandPublication . Neto, Berta; Rocha, A.M.; Girão, J.P.; Dionísio, Rogério Pais; Reis, Cláudia; Chatzi, S.; Bonada, F.; Lazaro, J.; Teixeira, António; André, P.S.In this paper, we investigate through simulation the feasibility of amplification solutions for WDM ring PON encompassing C+L transmission bands. The system under analysis is composed by a bidirectional pump at 1480 nm with 1 W of power in each direction and 16 channels (8 C band + 8 L band). The simulation describes an 80 km WDM ring with 8 nodes in which 2 channels are added/dropped. Two scenarios were implemented, one with simple Raman amplification that considers that all the pump power travels along the ring being selected the optimal order to drop channels and another with C- band in line EDFA in the link mid length that performs and additional amplification on C band signals. The results of both approaches are compared and their suitability for practical PON is analyzed.
- Dual MZI-SOA with serial configuration for quadrature phase modulationPublication . Dionísio, Rogério Pais; Reis, Cláudia; Pavlovic, Natasa B.; Nogueira, Rogério; Teixeira, AntónioA novel generation scheme of QPSK format using dual MZI-SOA in serial configuration is presented. The feasibility of 20 Gb/s QPSK signal with coherent detection is experimentally shown.
- Ferramenta de simulação para análise espectral de redes de BraggPublication . Dionísio, Rogério Pais; Lima, Mário J.; Rocha, J.R. Ferreira da; Pinto, J.L.; Teixeira, AntónioAs redes de Bragg (FBG) tornaram-se componentes importantes na redes de comunicações ópticas, pois permitem a realização de várias operações sem a necessidade de conversão opto-electrónica. Este artigo descreve uma ferramenta de software para simulação e caracterização de redes de Bragg por nós inteiramente concebida. A interface gráfica foi programada utilizando o ambiente GUIDE do Matlab. É assim possível analisar um leque variado de FBGs, tendo em consideração os efeitos secundários provocados pela variação do índice de refracção médio, durante o processo de fabrico.
- All-optical XOR based on integrated MZI-SOA with Co and counter-propagation schemePublication . Reis, Cláudia; Dionísio, Rogério Pais; Neto, Berta; Teixeira, António; André, P.S.In this work we present a review of all-optical XOR gates based on Mach-Zehnder Interferometer with Semiconductor Optical Amplifiers (MZI-SOA), using NRZ modulated signals driven at 10 Gbit/s. The performance of two alternative schemes for logical XOR gates implementation is demonstrated through numerical simulations and experimentally. The extinction ratio shows high operation performance with low degradation.
- Efficient dynamic modeling of reflective semiconductor optical amplifierPublication . Vujicic, Zoran; Dionísio, Rogério Pais; Shahpari, Ali; Pavlovic, Natasa B.; Teixeira, AntónioRSOA is considered a strong candidate to play an important role in realizing the next generation WDM PON, based on the wavelength reuse concept. Therefore, accurate and efficient modeling of RSOA is of significant importance. We present a time-domain wideband model for simulation of spatial and temporal distribution of photons and carriers in a bulk RSOA. A trade-off between the accuracy and the computational efficiency of the model is studied. Multi-objective genetic algorithm is utilized for parameter extraction. Experimental validation has been performed for continuous wave input, NRZ and QPSK signaling pulses up to 40 Gb/s of bit rate, in both amplification and remodulation regimes. Saturation, noise, chirp and signal broadening are successfully predicted, while reducing the computational time compared to other wideband models.
- C+L band gain equalization for extended reach WDM-ring PON using hybrid Raman/in line EDFA amplificationPublication . Neto, Berta; Rocha, A.M.; Girão, J.P.; Dionísio, Rogério Pais; Reis, Cláudia; Chatzi, S.; Bonada, F.; Lazaro, J.; Teixeira, António; André, P.S.In this paper, we investigate by simulation the feasibility of gain enlargement and equalization on extended reach WDM-ring PON by means of hybrid Raman/EDFA amplification. The system under analysis is composed by a bidirectional pump at 1480 nm and 16 channels (8 C band + 8 L band). The simulation describes an 80 km WDM ring with 8 nodes in which 2 channels are added/dropped. The results demonstrate gain equalization with a ripple of 2.54 dB over a bandwidth of 50 nm by using a 1480 nm bidirectional pump with 1 W and spans of EDF with a total length of 22 m.
- Advanced optical modulation and format conversionPublication . Dionísio, Rogério Pais; Teixeira, António; Nogueira, RogérioOver the years, the increased search and exchange of information lead to an increase of traffic intensity in todays optical communication networks. Coherent communications, using the amplitude and phase of the signal, reappears as one of the transmission techniques to increase the spectral efficiency and throughput of optical channels. In this context, this paper present a survey on format conversion of modulated signals using MZI- SOAs, based exclusively on all-optical techniques through wavelength conversion. We also present two proposal using all-optical techniques: One for the conversion of amplitude modulation signals to a continuous phase modulation format, and another technique for the conversion of OOK signals to QPSK and QAM signals. Both approaches are experimentally validated.
- Parametric impairments analysis of all-optical format conversion techniques with a MZI-SOAPublication . Dionísio, Rogério Pais; Nogueira, Rogério; Teixeira, AntónioThis paper proposes a new methodology for the generation of quadrature amplitude modulation signals, based on all-optical processing from nonlinear interferometric devices. The degradation of the systems performance is numerically analyzed, as a function of operational parameter’s unbalance and physical impairments of the system. The results shows that the probe laser power and the coupling factor of optical couplers are the most sensitive parameters of the proposed format conversion system.