Fig. 1. Schematic of phase-demodulated Φ-OTDR structure based on heterodyne coherent detection

Fig. 2. Simulated interference fading of signals in different cores

Fig. 3. Relationship between the SNR improvement and number of diversity

Fig. 4. Experimental setup of distributed acoustic sensing based on a multi-core fiber

Fig. 5. Relationship between the differential phase of one core and four cores and distance

Fig. 6. Differential phase of the aggregated signal in four cores at the disturbance location

Fig. 7. PSD of SMF and MCF at the frequency of 2.5 kHz

Fig. 8. PSD between SMF, one core and four cores in MCF at the disturbance location

Fig. 9. PSD between one core and four cores in MCF with the 8 kHz disturbance frequency

Fig. 10. PSD between each core and four cores in MCF without disturbance