Abstract

Temperature or strain sensing in long-range (> 70 km) Brillouin Optical Time Domain Analysis (BOTDA) below 2 meter resolution cannot be trivially achieved due to numerous matters such as fiber attenuation, self-phase modulation, depletion, resolution-uncertainty trade-offs, etc. In this paper we show that combining Raman assistance and the Differential Pulse-width Pair (DPP) technique sub-metrical resolution is achievable in a BOTDA over 100 km sensing range. We successfully demonstrate the detection of a 0.5 meter hot-spot in the position of worst contrast along the fiber.