16-QAM Signal Transmission with Bi-GRU Equalizer in Photonic Terahertz Communication System at 325-GHz

We propose a nonlinear equalization scheme for photonic terahertz communication systems based on bi-directional gated recurrent unit (bi-GRU). The simulation experiment results demonstrate that the bi-GRU equalizer enables 80Gbps 16QAM signal generation with a 325GHz terahertz band back-to-back transmission. Comparatively, the bi-GRU equalizer outperforms the constant modulus algorithm (CMA) equalizer, bi directional long short term memory (bi-LSTM) equalizer, and GRU equalizer in terms of improving the Q factor. Specifically, the bi-GRU equalizer increases the maximum Q factor by 2.05dB compared to the traditional CMA equalizer.