A novel distributed interferometer for security monitoring of ultra-long-distance submarine optical cables

Submarine optical cables are important in global communication, but existing security monitoring methods cannot ensure the information security of ultra-long-distance submarine optical cables. In this paper, a novel dual-wavelength unidirectional circular propagation asymmetric Mach-Zehnder interferometer (UCAMZI) is proposed. Characterized by wide dynamic range, ultra-long detection distance, high frequency response, UCAMZI is compatible with existing submarine repeaters. The performance is demonstrated by experiments. When the sensing distance is 150 km, the location error is approximately 56 m. The response frequency can reach 37 kHz. UCAMZI has the potential to reach a detection length over 1000 km, which holds broad prospects in the security monitoring of ultra-long-distance submarine optical cables.