Smart Cables

Distributed Fiber Sensing (DFS), Distributed Acoustic Sensing (DAS), State of Polarization (SoP), and Branching Units (BUs) are technologies and components integral to potential SMART SFOC system designs.

• • Distributed Fiber Sensing:Uses optical fibers as distributed sensors to detect physical changes such as strain or temperature along the cable.

• • Distributed Acoustic Sensing:A form of DFS that detects acoustic vibrations by interpreting backscattered laser pulses in the fiber optic cable.

• • State of Polarization:Measurement of the polarization characteristics of light in the fiber, used for enhanced environmental sensing.

• • Branching Unit:An underwater device enabling the cable to branch off into multiple paths, supporting modular sensor array deployment and network expansion at strategic locations.

• • Point Sensors: Devices that provide precise measurements at single, specific locations along the cable system. Examples include Fiber Bragg Grating (FBG) sensors and interferometric sensors embedded within SMART Nodes, as well as traditional electronic sensors attached to cable infrastructure. Point sensors deliver highly accurate local data that complement the broad, continuous monitoring provided by distributed sensing technologies like DAS.
  • Observatory Nodes: Cabled ocean observatory nodes are designed for specific experiments and use industry standard wet mate connections as well as bespoke connections to the individual nodes. The oil and gas industry pioneered the use of cabled nodes and wet mate connections to enhance oil production and environmental compliance and safety. Unlike embedded Point Sensors, the nodes offer flexibility by allowing researchers to customize sensor types and locations based on evolving scientific needs. For instance, they might be installed on a branch extending from the main cable to monitor specific marine ecosystems or localized seismic events. This modularity reduces the need for full cable redesigns and enables targeted data collection. The concept is like adding “plug-in” instruments to a network node, facilitating easier maintenance and technology refreshes over the cable’s operational life.
• • • • • • In-Line Nodes: These nodes are an integrated sensor package embedded inside “empty” submarine cable fiber optic repeaters and have recently entered the commercial prototyping phase. These nodes contain multiple Point Sensors, such as temperature, pressure, and seismic acceleration sensors, that provide discrete, high-accuracy environmental measurements at each deployed location along the cable.SMART Nodes: Devices located along the cable route at any spacing to accommodate Point Sensor requirements of power and telecommunications. These nodes can be arranged along the primary cable route or off branches in a variety of configurations. They enable the use of modular, attachable sensor units that can be added at initial deployment or during upgrades. Examples of SMART Nodes are In-Line Nodes and Observatory Nodes, described below:

• SMARTBU Arrays: Simple to complex arrangements of SMART Nodes and associated Point Sensors. SMARTBU Arrays consist of multiple SMART nodes distributed systematically along the branches to create a networked system of environmental monitors. By deploying arrays at regular intervals, concentrating them on specialized branches, scientists gain comprehensive spatial coverage and enhanced resolution of oceanographic and seismic phenomena. For example, an array could detect subtle shifts in ocean currents or early signs of undersea earthquakes across vast areas around Antarctica. These arrays support complex data analysis and modeling efforts by providing dense, multi-point measurements rather than readings solely along the main cable route.