When we talk about fiber-optic cables, you probably think mainly of fiber-optic internet. But that’s certainly not the only thing these strong cables are good for. In addition to being very strong, fiber optic cables are also highly sensitive to vibrations and temperature changes, among other things. They are super-sensors that can be used to monitor levees, detect undersea earthquakes, transmit energy, and even to “listen.” Want to learn more about using fiber optic cables as sensors? Then read on!
Fiber optics is more than just fast internet
More than half of Dutch households now use high-speed fiber-optic internet. It’s no surprise, then, that this is the first thing that comes to mind when we talk about the material. It’s a versatile powerhouse that can transmit information literally at the speed of light. Of course, there’s more to it than just building networks. Today, fiber-optic cables are also regularly used for fiber sensing, but what exactly does that entail?
Fiber Sensing: Using Fiber-Optic Cables as Sensors
One of the potential applications of fiber optics that often surprises people is the use of fiber optic cables as sensors, also known as fiber sensing. Fiber sensing makes it possible to detect vibrations, temperature differences, and stretching or contraction. This works with extreme precision, even at nearly the molecular level. Fiber optics have a very pure composition, which is one of the reasons they are highly sensitive. The vibration frequency of molecules in the fibers of the material changes measurably under environmental influences, such as changes in temperature, strain, contraction, pressure, or sound. Using the light in the fiber-optic cables, one can track these changes in the molecules and thus measure them!
How does that work?
Normally, a small percentage of the light you send through a fiber is reflected by the glass molecules. If somewhere along the way a factor changes the force acting on the fiber, this directly affects the movement of the molecules in the fiber and, consequently, the reflection of the light. The result is that slightly more light is reflected back than usual, which can be immediately detected with the proper equipment. Because fiber-optic cables are so sensitive, one can not only see that something is changing somewhere in the cable, but also pinpoint exactly where in the cable the change is occurring, down to the centimeter. This, too, can be calculated based on the speed of light traveling through the cables. In this way, the cause of a network disruption is just as easy to trace. Every source of a fault has its own distinct type of reflection, which is highly recognizable. As a result, it becomes clear in no time exactly where a fault in the cable network is located and where it originates.
Examples of Fiber Sensing Applications
Fiber sensing is used today for a wide variety of purposes. In the Netherlands, for example, we use fiber-optic cables to monitor when a dike begins to subside. By laying the cables beneath dikes, we know exactly when and where the dike is subsiding or may begin to subside. Another application of Fiber Sensing is detecting overheating or excessive heating in manufacturing processes or machinery. This helps prevent machine downtime, ensuring that production processes don’t come to a standstill. Did you know that Nike even uses Fiber Sensing to develop and test new sneakers and athletic shoes? They use it to measure which parts of the shoes are subjected to the most tensile stress!