A Design Method of In-band Communication Link in Power-Over-Fiber Application System

Power-over-fiber (POF) technique is a commonly way to transmit power externally into the low-power remote modules in specific distributed measurement systems. This paper briefly analyzes the technical characteristics and application limitations of different implementations of In-band communication used in the POF system. Based on the analysis of the characteristics of key components such as laser diode (LD) and photoelectric converter (PPC), this paper proposes a closed-loop digital modulation method that takes the characteristics of photovoltaic voltage signals as feedback to control the drive current of LDs, and then the In-band communication link over the power supply fiber can be established. After that, this paper explains the architecture design, control circuit, feed-back demodulation design and closed-loop control software design of the POF system with In-band downlink capability. The specific test verifies that the proto-type realizes the downlink communication in POF system at 1 Mbps rate between the host and remote module which runs in industrial temperature environment. The method can meet the communication requirements of parameter configuration, sampling calibration and other functions in the industrial distributed measurement system.