Quasi-Distributed Water Detection Sensor Based On a V-Grooved Single-Mode Optical Fiber Covered with Water-Soluble Index-Matched Medium

The V-grooved single-mode fiber in which a surface part of the core was removed was investigated as a quasi-distributed water detec-tion sensor. In the normal state, the V-grooved region is filled and covered with a specific RI (Refractive Index)-matched medium, and the sensor experiences minimal optical loss. As water invades the V-grooved region, the material is dissolved and removed, and a con-siderable optical loss occurs owing to the large RI difference between the fiber core and water. The experimental results showed the feasibility of the device as a sensor element of the quasi-distributed water detection sensor system based on general optical time domain reflectometry (OTDR)