Research on high-speed multi-modulation coherent optical communication technology

In communication networks, in order to obtain better bit error rate performance, it is necessary to use a suitable modulation format according to the link characteristics. Therefore, coherent receivers are faced with the need to receive signals in multiple modulation formats. Coherent optical communication systems can make full use of the amplitude, phase, polarization state, time and frequency of optical carriers for signal modulation. Digital signal processing is an important part of coherent receivers and the key to improving receiving sensitivity. In order to achieve multi-modulation reception, it is necessary to study digital signal processing solutions for multi-modulation signals. This article conducts theoretical and experimental research on the modulation, demodulation methods and digital signal processing algorithms of highspeed coherent optical communication systems. A parallelization scheme for multi-modulation format digital signal processing is proposed. The offline experimental verification results of the parallelized multi-modulation digital signal processing algorithm show that at the forward error correction (FEC) bit error rate threshold, the signal reception sensitivity is 2dB higher than that of the QPSK modulation format.