Distributed Temperature Measurement With Chaotic Brillouin Optical Coherence Domain Reflectometry

In the distributed optical fiber sensing system, optical fiber is used as thesensing element and the transmission medium. Distributed sensing measurementcan be realized by detecting the backscattered scattering signal. Distributedoptical fiber sensing technology has important applications such as construction,mining, petroleum, electric power, aerospace etc. Distributed optical fibersensing technology based on Brillouin scattering has the advantages ofsimultaneous measurement of strain and temperature, along with the highprecision. However, the drawback of these methods is that they cannotsimultaneously achieve high spatial resolution and long distance in sensingmeasurements.This paper proposes a chaotic Brillouin optical coherent domain reflectometry.The main works are summarized as follows:(1)We introduced the basic working principle of single point sensor, quasidistributed sensor and distributed optical fiber sensor. And we analyzed the advantages and disadvantages of the Brillouin optical time domain technologiesand the Brillouin optical correlation domain technologies. Then, we proposed anovel method which can realize high spatial resolution and long measurementrange at the same time.(2) We analyzed the sensing principle of chaotic Brillouin optical coherencedomain reflectometry in theory due to the low coherence length characteristicsof chaotic laser.(3) We have studied the generation of chaotic laser and the characteristics ofchaotic Brillouin scattering light. And we have studied the relationship betweenpower injection, modulation amplitude, the polarization in optical fiber and thechaotic Brillouin scattering light, respectively.(4) We set up the temperature sensing experiment system about chaoticBrillouin optical coherence domain reflectometry. The working principle wasintroduced in details. Then we obtained the relationship of the chaotic Brillouinscattering light and temperature. Finally, we did the temperature sensingexperiment and obtained the temperature distribution along the fiber under test.(5) We analyzed and discussed the advantage and the existing problems of thisscheme. At last, we put forward to some improved suggestion at the next work.