Multimode Interference Sensors for Static and Dynamic Monitoring

Abstract

Because of their simplicity and lower cost of realization, intensity-based optical fiber sensors are of great industrial and research interest. A class of these sensors uses the interference of waves propagating in a fiber structure to induce intensity variations that are then recovered using direct detection. These in-fiber interferometers make use of the sensitive phase variations of waves propagating in fibers to produce intensity variations, resulting in better sensitivities compared to many pure intensity-based sensors. This chapter addresses simple optical fiber sensors based on modal interference in multimode optical fibers: their working principles, potential applications, and challenges for industrial sensor realizations. Different sensor structures and approaches to sensing have been developed. These are reviewed and contrasted to one another. Sensor applications and multiplexing schemes are then addressed and compared.