FIBEROPTIC DUAL-TECHNIQUE SENSOR FOR SIMULTANEOUS MEASUREMENT OF STRAIN AND TEMPERATURE

Polarimetric and two-mode differential interferometric schemes incorporated in an elliptical-core fiber are able to resolve strain and temperature simultaneously with resolutions of 10 mum/m and 5-degrees-C, respectively. A technique, based on the evaluation of the condition number of a matrix, is shown to be useful in evaluating comparative merits of multiparameter sensing schemes. The determinant of the beat length matrix is expressed in terms of mode propagation constants, and a method for designing specialized fibers suitable for simultaneous measurement of strain and temperature is proposed. Experimental results for four fibers are presented and cross-sensitivity issues are discussed.