## 1 Introduction
With the gradual maturity of MCF-based techniques, real-time CDM transmission using commercial 400 Gb/s optical transport network (OTN) transponders, as well as multiple field trials over experimental MCF cables, have been demonstrated [2; 13; 18; 19]. These works undoubtedly prove the feasibility of integrating MCFs into next-generation optical networks and promote the field implementation of MCFs in terrestrial optical fiber cable systems. Furthermore, benefiting from the inherent advantage of MCFs that they contain multiple parallel fiber core channels within a single fiber, MCFs can also enable various capacity-consuming services, especially ICS techniques. The multiple fiber core channels in an MCF provide sufficient channel resources for simultaneously achieving sensing functions, and multiple MCF-based ICS systems have been reported. For instance, a full-duplex ICS system utilizing distributed fiber sensors over the spare cores of MCFs has been demonstrated, which is compatible with commercial optical modules as well as fiber sensors, and it can realize the real-time monitoring of environmental parameters [20]. Additionally, a field trial of high-resolution distributed fiber sensing over MCF cable in the city of L'Aquila, Italy, using a MIMO distributed acoustic sensing (DAS) technique has been reported [1]. Leveraging the multiple parallel core channels in an MCF and advanced MIMO-DAS, the system achieves a 2 m spatial resolution and 1 mHz-380 Hz acoustic bandwidth, which can effectively localize and identify construction-related events in metropolitan areas. In addition, a high-speed field trial of an ICS system over deployed seven-core fiber cable has also been experimentally demonstrated, which reached a large capacity of 234 Tb/s (net 187.49 Tb/s) while monitoring traffic surrounding the deployed MCF cable [2]. These remarkable MCF-based ICS techniques significantly advance the evolution of optical networks toward a large capacity and high operational security. However, to the best of our knowledge, a real-time field trial of an ultra-high-speed ICS transmission system using 1.2 Tb/s OTN transponders over deployed MCF cable has not been reported so far. Fully exploring the transmission capacity and sensing potential of MCFs, and promoting their field implementation in next-generation ultra-high-speed highly reliable optical transmission networks, is highly desired. In this paper, we demonstrate an ultra-high-speed ICS OTN system utilizing 130 Gbaud probability constellation shaping 64-ary quadrature amplitude modulation (PCS-64 QAM) 1.2 Tb/s OTN transponders and dual-polarization quadrature phase shift keying (DP-QPSK) 200 Gb/s ICS optical transponder units (OTUs) with polarization-based sensing techniques over a field-deployed seven-core fiber cable for the first time. A real-time 267.8 Tb/s 2 \(\times\) 70.76-km transmission is achieved using only C-band signals thanks to the high-performance 1.2 Tb/s OTN transponders. And the ICS system can sense environmental disturbances to the MCF cable such as shaking, striking, and so on in real time through the 200 Gb/s ICS OTUs by monitoring the changes in the polarization state of the received signals. The transmission capacity can also be further enhanced by incorporating L-band signals. This work demonstrates the feasibility of simultaneously achieving ultra-high-speed data transmission and the real-time sensing of environmental disturbances over field-deployed MCF cable and is beneficial to next-generation ultra-high-speed highly reliable optical transmission networks. The rest of this paper is organized as follows. In Section 2, we present our proposed ultra-high-speed MCF-based ICS OTN prototype system. Section 3 shows the ultra-high-speed 130 Gbaud 1.2 Tb/s OTUs and the 200 Gb/s ICS OTUs utilized in our field trial. In Section 4, the field-deployed seven-core MCF cable is introduced. Section 5 presents the experimental results of the field trial.