All-Photonic 20-MHz Clock for Latency Monitoring in a 5G Network at 10Gbps over Optical Fiber

Innovation and advancement in technologies such as self-driving cars, machine learning, remote health and factory floor automation have led to extremely stringent next-generation communication requirements. For instance, in a self-driving car, sensor data may be streamed to a cloud-based computer. Decentralized machine learning relying on augmented data may be used to control the vehicle. Large amounts of sensor data, along with the real-time nature of the applications, demand requirements on the 5G networks needed to support applications such as this. Specifications for 5G networks require extremely low end-end latency <1ms. This latency requirement is tenfold more stringent than the 4G requirement of <10ms. In this paper, we present a novel clock method for tracking and monitoring 5G latency. The method is all-optical, can accurately track <1ms latency, and is spectrally efficient. We experimentally demonstrate generation of a 10 Gbps intensity-modulated data signal with 12.3 GHz carrier frequency, embedded with 20 MHz phase-modulated clock. The signal is successfully transmitted over 26.6 km of nonzero dispersion shifted fiber (NZDSF) single-mode fiber at 1550 nm. Error-free forward error correction data transmission was archived with 12.05 dB receiver penalty. Phase noise of −40.55dBc/Hz and −77.84dBc/Hz were attained at 1 Hz and 1 kHz offsets, respectively, for the clock.