510-Gbps 322-GHz Photonics-Aided Terahertz Wireless Transmission System With MIMO Embedded Adaptive Phase Recovery Equalizer
Jianyu Long, Jianjun Yu, Chen Wang, Long Zhang, Bohan Sang, Ying Wu, Xiongwei Yang, Yi Wei, Kaihui Wang, Wen Zhou, Junjie Ding, Jiao Zhang, Min Zhu
Abstract
Photonics-aided terahertz (THz) technologies in capable of supporting large signal bandwidths are promising in future ultrahigh-speed wireless communication systems, especially the THz-over-fiber (ToF) indoor applications. <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2 \times 2$ </tex-math></inline-formula> multiple-input-multiple-output (MIMO) architecture for polarization-division multiplexing (PDM) can further double the system capacity with polarization dimension, while bringing more crosstalk and impairments to signal recovery. In this article, we propose to apply a MIMO equalizer with embedded adaptive phase recovery (eAPR) and independent channel processing (ICP) (MIMO-ICP-eAPR) digital signal processing (DSP) to better compensate for the crosstalk and impairments in a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2 \times 2$ </tex-math></inline-formula> MIMO PDM THz transmission system. With the novel MIMO-ICP-eAPR and photonics-aided THz-wave technologies, we experimentally demonstrate 60-GBaud probabilistically shaped (PS)-64QAM signal transmission over 20-km fiber and 3-m THz wave at 322 GHz in the air, empowered by a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2 \times 2$ </tex-math></inline-formula> MIMO antenna array for PDM technologies. The adaptive phase recovery (APR) integrated with MIMO equalizers can provide a better performance compared to separately applying MIMO equalizers followed by APR. Compared to the APR-separated counterpart, the proposed MIMO-ICP-eAPR can improve the input power sensitivity by 0.6 dB. Furthermore, even without ICP for mitigating IQ crosstalk, the MIMO-eAPR approach still shows performance enhancement compared to MIMO followed by APR. To the best of our knowledge, a record-breaking net rate of 510 Gbps per wavelength for a THz-wave transmission system with PS signals is reached. This work can provide fiber-THz architecture as well as a solution for future THz applications.