片端光入射システムとして世界最速動作を達成した「位相検波ブリルアン光相関領域反射計」に関する水野助教の招待総説論文が Optical Review に掲載されました。
Y. Mizuno, N. Hayashi, H. Fukuda, and K. Nakamura, “Phase-detected Brillouin optical correlation-domain reflectometry,” Opt. Rev., vol. 25, no. 3, pp. 473-485 (2018) <invited review>.
Optical fiber sensing techniques based on Brillouin scattering have been extensively studied for structural health monitoring owing to their capability of distributed strain and temperature measurement. Although a higher signal-to-noise ratio (leading to high spatial resolution and high-speed measurement) is generally obtained for two-end-access systems, they reduce the degree of freedom in embedding the sensors into structures, and render the measurement no longer feasible when extremely high loss or breakage occurs at a point of the sensing fiber. To overcome these drawbacks, a one-end-access sensing technique called Brillouin optical correlation-domain reflectometry (BOCDR) has been developed. BOCDR has a high spatial resolution and cost efficiency, but its conventional configuration suffered from relatively low-speed operation. In this paper, we review the recently developed high-speed configurations of BOCDR, including phase-detected BOCDR, with which we demonstrate real-time distributed measurement by tracking a propagating mechanical wave. We also demonstrate breakage detection with a wide strain dynamic range.