With increased demand for bandwidth-hungry applications such as video-on-demand, wavelength-division-multiplexing passive optical network (WDM-PON) has become a strong contender in overcoming the last mile bottle neck. However, the wide-scale deployment of WDM-PONs has been delayed mainly due to the high cost of wavelength-specific optical components. To realize cost-effective WDM-PONs, various wavelength-independent, so called colorless architectures, have been developed so that all the subscribers can have identical optical network units (ONUs). In such WDM-PONs, however, single-fiber bidirectional transmission results in degradation of system performance caused by interference between the signals and backreflections. This thesis investigates the impact of backreflections on single-fiber bidirectional WDM-PONs. A WDM-PON with various optical line terminals (OLTs) and colorless ONU configurations is presented. The dependence of the power penalty, caused by backreflections, on a variety of parameters is investigated. This includes parameters such as the source linewidths, receiver bandwidth, transmission line loss (TLL), ONU gain, chirp effect at the ONU and optical return loss (ORL), in various WDM-PON configurations. The WDM-PON with continuous wave (CW) seed light and remodulation schemes are both presented and studied experimentally. The impacts of the backreflections on the single-fiber bidirectional WDM-PON with various OLT and ONU configurations are compared and analyzed accordingly.

With increased demand for bandwidth-hungry applications such as video-on-demand, wavelength-division-multiplexing passive optical network (WDM-PON) has become a strong contender in overcoming the last mile bottle neck. However, the wide-scale deployment of WDM-PONs has been delayed mainly due to the high cost of wavelength-specific optical components. To realize cost-effective WDM-PONs, various wavelength-independent, so called colorless architectures, have been developed so that all the subscribers can have identical optical network units (ONUs). In such WDM-PONs, however, single-fiber bidirectional transmission results in degradation of system performance caused by interference between the signals and backreflections. This thesis investigates the impact of backreflections on single-fiber bidirectional WDM-PONs. A WDM-PON with various optical line terminals (OLTs) and colorless ONU configurations is presented. The dependence of the power penalty, caused by backreflections, on a variety of parameters is investigated. This includes parameters such as the source linewidths, receiver bandwidth, transmission line loss (TLL), ONU gain, chirp effect at the ONU and optical return loss (ORL), in various WDM-PON configurations. The WDM-PON with continuous wave (CW) seed light and remodulation schemes are both presented and studied experimentally. The impacts of the backreflections on the single-fiber bidirectional WDM-PON with various OLT and ONU configurations are compared and analyzed accordingly.

With increased demand for bandwidth-hungry applications such as video-on-demand, wavelength-division-multiplexing passive optical network (WDM-PON) has become a strong contender in overcoming the last mile bottle neck. However, the wide-scale deployment of WDM-PONs has been delayed mainly due to the high cost of wavelength-specific optical components. To realize cost-effective WDM-PONs, various wavelength-independent, so called colorless architectures, have been developed so that all the subscribers can have identical optical network units (ONUs). In such WDM-PONs, however, single-fiber bidirectional transmission results in degradation of system performance caused by interference between the signals and backreflections. This thesis investigates the impact of backreflections on single-fiber bidirectional WDM-PONs. A WDM-PON with various optical line terminals (OLTs) and colorless ONU configurations is presented. The dependence of the power penalty, caused by backreflections, on a variety of parameters is investigated. This includes parameters such as the source linewidths, receiver bandwidth, transmission line loss (TLL), ONU gain, chirp effect at the ONU and optical return loss (ORL), in various WDM-PON configurations. The WDM-PON with continuous wave (CW) seed light and remodulation schemes are both presented and studied experimentally. The impacts of the backreflections on the single-fiber bidirectional WDM-PON with various OLT and ONU configurations are compared and analyzed accordingly.

[pt] Os efeitos que causam limitações nas comunicações ópticas referentes a polarização se resumem essencialmente na Dispersão dos Modos de Polarização (PMD), nas Perdas Dependentes da Polarização (PDL), e no Ganho Dependente da Polarização (PDG). Estes efeitos podem aparecer na transmissão de forma isolada ou combinada, gerando distorções no sinal. Primeiramente estes efeitos foram estudados individualmente, cada efeito sendo analisado e quantificado sob diversos aspectos. Através de uma analise teórica e experimental foi proposto uma nova técnica de medida de penalidade de potência envolvendo os efeitos estudados. Depois de um estudo detalhado sobre os efeitos isolados, analisou-se os efeitos combinados de PMD e PDL. Diversos emuladores de PMD, elementos com PDL variável e emuladores de PMD e PDL fizeram parte de um longo estudo sobre estes efeitos combinados. Procurou-se ressaltar a importância e os cuidados necessários que se deve tomar para a construção de um emulador de PMD. Na última etapa, foram estudados os efeitos de PMD e PDG oriundos de um sistema utilizando amplificação Raman. Desta forma foi possível evidenciar, caracterizar e relacionar os efeitos da polarização nas fibras ópticas. / [en] The polarization effects that cause limitations in optical communications are essentially the Polarization Mode Dispersion (PMD), the Polarization Dependent Loss (PDL), and the Polarization Dependent Gain (PDG). These effects can appear either isolated or in combinations, generating signal distortion. These effects were first investigated individually under different experimental situations and then combined effects were studied. A new technique for measuring the power penalties corresponding to these effects was proposed. The combined effects of PMD and PDL in PMD emulators were evaluated and quantified. Thumb rules for the manufacture of PDL-free emulators were proposed. The effects of PMD and PDG originated from Raman amplification were also studied and compared with theoretical predictions.