The Optical Fibre Sensor: A Theoretical and Experimental View
Abstract:Fibre Optic Sensors are a fast-growing technology in recent years, and this area of photonics cuts across various aspects of life. Its prominent features enable it to stand out from other conventional methods of sensing, making them unique for various applications. In this study, a technique was developed to measure vibration along a fibre cable when there was an external/environmental perturbation. Metal analysis technique was employed which resulted in the derivation of the mathematical equation of light intensity in a fibre using the general Helmholtz equation. It was observed from the equation that light intensity, when perturbed, can cause a change in the phase as light travels through the fibre. The data obtained showed an increase in attenuation (loss) in the fibre cable when it undergoes perturbation, which is as a result of vibration. It is also observed that there is a phase shift, which is recorded by the OTDR as described in the theory (mathematical equation). The result obtained from this study shows that vibration can be measured by means of a fibre optic sensor using this technique, and the measured data obtained conforms with the theoretical result and is found to be successful. Although multimode fibre is preferred to single-mode fibre for short distances when taking measurements, this technique can also be used to achieve this and further measure the frequency of vibration using an OTDR.