Dual-Channel Fiber Optic Current Sensor Based on Two-Carrier Modulation Technique

An innovative dual-channel fiber optic current sensor (FOCS) based on two-carrier modulation technique is proposed and experimentally demonstrated. The system enhances standard reflective FOCS by incorporating an additional sensing channel, thereby effectively using key optical devices without incurring significant additional costs. By rationally designing the relationship between the frequencies of the two carriers and the transmission fiber length of two channels, simultaneous current measurement without crosstalk can be achieved. The experimental results demonstrate that the current measurements from both channels are highly independent and exhibit a linear variation with respect to the applied current, with an $R^{2}$ coefficient exceeding 0.9999. In the experiment, the two channels have a maximum current sensitivity of 1.1 and 0.8 mV/A, respectively. In addition, the system has excellent long-term stability, as evidenced by signal fluctuations of 2.68 and $1.69~\mu $ V for the two channels over a 30-min duration. The proposed scheme offers a promising solution for advancing the development of multichannel current measurement and holds potential for practical applications in the power grid.