Fiber Bragg grating first- and second-order diffraction-wavelength-based transducer-optimized design

Several experimental demonstrations of a unique Fiber Bragg Grating (FBG) based transducer for strain and temperature have been made. The proposed technique is based on the inscription of an unique uniform FBG what presents first- and second-order diffraction wavelength response. The measurement of the wavelength change at both wavelengths allow the design of a simple and efficient fiber optic based transducers. Although strain-temperature discrimination feasibility have been proved previously, the errors associated to the transfer matrix must be improved to achieve a similar performance than other FBG based discrimination techniques. Up to our knowledge, theoretical analysis which allows an optimized transducer design have not been made. In this communication a generalized study of the behavior of two wavelength measurement based transducers is going to be made. Physical parameters which are involved in the transducer construction are going to be analyzed and a suitable technique for optimal transducer design is going to be proposed. Several conclusions about the relation among each FBG based transducer parameter and the transfer matrix condition are going to be presented. The measurement errors associated to this physical parameters will be derived allowing the design of optimized specific transducers