Slope-assisted Raman distributed optical fiber sensing

Raman distributed optical fiber sensing is required to achieve accurate temperature measurements in a micro-scale area. In this study, we first analyze and demonstrate the pulse transmission feature in the temperature variation area and the superposition characteristics of Raman optical time-domain reflectometry (OTDR) signals by numerical simulation. The equations of superimposed Raman anti-Stokes scattered signals at different stages are presented, providing a theoretical basis for the positioning and physical quantity demodulation of whole optical fiber systems based on the OTDR principle. Moreover, we propose and experimentally demonstrate a slope-assisted sensing principle and scheme in a Raman distributed optical fiber system. To the best our knowledge, this is the first experimental demonstration of Raman distributed optical fiber sensing in a centimeter-level spatial measurement region.