Abstract

In traditional microbend sensors, the amplitude of a series of small periodic bends in an optical fiber changes with the measurand. In this new approach, the prebent fiber is embedded in a compliant material, and the sensor is designed such that the changing measurand causes changes in the spatial frequency of the bends. Because the microbending loss is a highly resonant effect, very high sensitivity can be obtained. Furthermore, the sharpness of the resonance curve is controlled by the Fourier transform of the physical deformation. In amplitude-type sensors, the shape is always small bends separated by short straight pieces, due to the nature of the deforming process. For a prebent fiber, the shape can be arbitrarily chosen, thus allowing design freedom in controlling sensitivity. This sensor is also expected to be more reliable and have longer life than amplitude-type sensors.

© 1993 Optical Society of America