Phasorial DPP-BOTDA sensor tolerant to non-local effects

Abstract

We introduce a modification of the differential pulse-width pair technique in a BOTDA sensor based on a phase-modulated probe wave and RF demodulation. This provides a differential Brillouin phasorial signal with high spatial and spectral resolution in both components (magnitude and phase-shift). Moreover, the use of a phase-modulated probe wave provides RF phase-shift measurements tolerant to the emergence of non-local effects. The combination of both techniques can lead to the development of long-range BOTDA sensors. Proof-of-concept experiments demonstrate RF phase-shift measurements with 1m spatial resolution over 50km and an uncertainty of 1.3°C at the worst contrast position. © 2014 SPIE.