Transmission of PAM4 signals in intra-datacenters connections with direct-detection and multicore fibers limited by inter-core crosstalk

• Autor(a) principal: Jorge, Inês Costa
• Data de Publicação: 2019
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10071/20182
• topic: Bit error rate; Inter-core crosstalk; Intra-datacenters connections; Multicore fiber; Outage probability; PAM4; Power penalty; Diafonia entre núcleos; Fibra multinúcleo; Indisponibilidade; Ligações em centros de dados; Penalidade de potência; Taxa de erro de bit; Engenharia de telecomunicações; Engenharia de sistemas; Linhas de transmissão; Transmissão de dados

Nowadays, traffic in datacenters has been dramatically increasing over the last few years. As such, it is necessary to scale the connections of the datacenters, to accommodate such increase of traffic. The solution proposed in this work is to use four-level pulse amplitude modulation (PAM4) and multicore fibers (MCFs) to support intra-datacenters connections. However, transmission in MCFs is significantly degraded by inter-core crosstalk (ICXT) between cores. In this work, the impact of ICXT on the performance of PAM4 transmission in short-haul directdetection links, emulating intra-datacenters connections, is analyzed. To evaluate the ICXT impact on the performance of the system, several metrics are used such as: bit error rate, eye-pattern analysis, power penalty and outage probability (OP). Our numerical results show that the ICXT levels that lead to 1 dB power penalty degradation with low skew-symbol rate product are at least 2.3 dB above the ones found with high skew-symbol rate product. For these crosstalk levels, the PAM4 system is probably unavailable with an OP above 102. To reach an acceptable reference OP of 3.8 103, the ICXT level must be reduced at least 5 dB, when compared to the ICXT level that leads to the 1 dB power penalty. Hence, the OP is an essential performance metric instead of the 1 dB power penalty to guarantee quality of service in PAM4 direct-detection systems supported by MCFs. Furthermore, comparing to OOK systems, a much higher ICXT level above 7.6 dB is required to achieve the same OP in the PAM4 system.