Co-transmission of radio frequency reference and data signal over multi-core fiber

Information and communication technology has continuously driven the demand for higher data transmission rates. At the same time, frequency synchronization technology also needs to continually adapt to the high-precision frequency references required between equipment in high-speed optical communication systems. However, existing time and frequency transmission technologies, which rely on the hardware-timestamp functions specified in IEEE1588, cannot meet the accuracy requirements for Precision Time Protocol (PTP) devices in 5G + or future 6G communications. Multi-core fiber, with its characteristics such as multi-channel transmission, superior symmetry, high integration, and versatility, is poised to become the preferred choice for next-generation communication fibers. There is a need to investigate the co-transmission of RF references and data signals based on multi-core fiber to further expand the capacity of communication data transmission and provide precise RF references for 5G + and future 6G communications. This paper proposes and experimentally demonstrates a novel approach for RF clock references and data signals co-transmission over a seven-core fiber on the same wavelength. By inserting an RF standard tone into the data signal spectrum through spectral modulation, we achieve co-transmission of a 10-MHz RF standard and 224-Gb/s dual-polarization 16-QAM signals over 1 km and 10 km seven-core fiber links based on frequency-synchronous optical network (FSON) architecture. The RF and data signals are received and demultiplexed entirely in the optical domain using a radio frequency and data signal demultiplexing (RFDSD) module. The measured 10-MHz frequency stability over 1 km and 10 km seven-core fiber links is better than commercial rubidium atomic clocks and it demonstrates the potential for picosecond-level clock dissemination within short-reach optical interconnects scenario. This work shows good performance in coherent demultiplexing of 224-Gb/s DP-16QAM signals with all tributaries demultiplexed below the 7% FEC threshold at receiver optical power levels of -19 dBm and − 18.5 dBm for 1 km and 10 km seven-core fiber links, respectively. Our approach provides a promising solution and theoretical foundation for next-generation high-speed, high-capacity, picosecond-level physical delay short-reach coherent optical interconnect applications.