All-optical modulation format conversion between 16-PSK and 8-PSK in elastic optical network

摘要

Elastic optical networks (EON) have emerged as a potential technology for developing next-generation optical networks, and modulation format conversion between multi-level modulation schemes is one of the critical techniques for improving the spectral efficiency and flexibility of EON. Towards this, an all-optical modulation format conversion between 16-PSK and two 8-PSK signals for optical channel aggregation and de-aggregation in EON at a data rate of 60 Gb/s has been proposed. The conversion system employs the four wave mixing (FWM) phenomenon for channel aggregation and de-aggregation in a highly non-linear fiber (HNLF) with third-order optical non-linearity. The performance of the system is assessed in terms of input-output constellation diagrams, bit error rate (BER), quality factor (Q-factor) and error vector magnitude (EVM) as a function of optical-signal-to-noise (OSNR) ratio, length of highly non-linear fiber (HNLF) and received optical power. It has been found that the conversion procedure for optical channel de-aggregation increases spectral efficiency to 2 bits/s/Hz and an improvement of OSNR of around 7 dB at BER of 3.8 x 10(-3) (FEC threshold) has been observed between the input 16-PSK signal and the output 8-PSK signals, reducing the complexity of the transmission and reception process at high data rates in EON. The simulation results demonstrate that the EVM curves of the 16PSK signal after aggregation and the 8-PSK signal after de-aggregation have a maximum degradation of 6%. The proposed conversion system has numerous potential applications in optical fiber transmission.