Pulse pre-pump method for cm-order spatial resolution of BOTDA

摘要

The distributed Brillouin scattering technique, using pulse width of 1 ns, that is, one order of magnitude smaller than currently available in commercial applications of BOTDA, was successfully implemented and examined in laboratory environment by Bao et al~2. However, the two main problems prohibits its commercial use, namely, the measurement setting must be modified each time the measurements object is changed, and, furthermore, long-range measurements cannot be effectively carried out due to substantial increase in signal noise level with the measurement distance. This paper presents a new technique, which overcomes both of these problems, by introducing the pre-pump pulse in front of standard laser pulse. Theoretical analysis clearly demonstrates that the cm-order distributed sensing, independent of the fiber length, can be realized. Moreover, a quantitative analysis of strain measurement accuracy is also presented.