Analysis on Spatial Intensity Modulation for Fiber-optic Sensor Applications

✍ Scribed by Jay Radhakrishnan; Mahmoud A. El-Sherif

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 303 KB
• Volume: 2
• Category: Article
• ISSN: 1068-5200
• DOI: 10.1006/ofte.1996.0013

✦ Synopsis

An inexpensive and sensitive technique for fiber-optic sensor applications is presented. It is based on analyzing the modal power distribution in multimode optical fibers, where light propagates in a set modal pattern defined by the boundary conditions of the waveguide. In the presence of external perturbations, the induced intermodal coupling will result in modal power redistribution. A theoretical approach to predicting external perturbations based on modal power analysis is discussed. A model for correlating changes in the modal power distribution with variations in the boundary conditions induced by external perturbations is developed for multimode fibers. This is a typical case of an intrinsic sensor where a multimode optical fiber is used as the sensing element. The intermodal coupling terms that are required to predict the modal pattern variation are derived under the weakly guiding assumption. Numerical results obtained by this approach are shown to be in agreement with experimental investigations.