Fiber optic evanescent field absorption sensor with high sensitivity and linear dynamic range

A novel fiber optic evanescent field absorption sensor having high sensitivity and linear dynamic range is proposed. High sensitivity is achieved by using a U-shaped probe while linear response is obtained by preventing surface reactivity of the silica core of the fiber with the solute molecules of the absorbing fluid. To prevent it, a thin film of a suitable polymer is developed on the bare core U-shaped probe. A good degree of reproducibility of the results is obtained. (C) 1998 Elsevier Science B.V. All rights reserved.