Simultaneous interrogation of interferometric and Bragg grating sensors

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Description/Abstract

We propose a new method for the simultaneous interrogation of conventional two-beam interferometers and Bragg grating sensors. The technique employs an unbalanced Mach-Zehnder interferometer illuminated by a single lowcoherence source, which acts as a wavelength-tunable source for the grating and as a path-matched filter for the Fizeau interferometer, thus providing a high phase resolution output for each sensor. The grating sensor demonstrates a dynamic strain resolution of ~0.05 με/√Hz at 20 Hz, while the interferometric phase resolution is better than 1 mrad/√Hz at 20 Hz, corresponding to an rms mirror displacement of 0.08 nm.