Recent achievements in BOCDA/BOCDR

Recent achievements in Brillouin Optical Correlation Domain Analysis/Reflectometry (BOCDA/BOCDR) are discussed. Through manipulating interference characteristics of continuous lightwave by modulating the frequency, stimulated Brillouin scattering can be generated position-selectively along an optical fiber. The position can be shifted by changing the FM frequency. Then, distributed measurement of temperature or strain can be realized. This is “Brillouin Optical Correlation Domain Analysis (BOCDA).” Distributed measurement of spontaneous Brillouin scattering can also be realized with a similar way, which is “Brillouin Optical Correlation Domain Reflectometry (BOCDR).” Superior functions have already been demonstrated, such as mm order spatial resolution, kHz order sampling speed, random accessibility to arbitrary multiple points, and discriminative and distributed measurement of strain and temperature. Applications of the techniques have also been demonstrated, including structural health monitoring of aircrafts.