Water penetration sensing wavelength tunable OTDR

A method for sensing water penetration into optical cable using a wavelength tunable optical time domain reflectometers (OTDR) is proposed. The reflectivity at every Fabry-Perot connector gap contained in a monitoring fiber has periodic wavelength dependence. It is shown experimentally that water penetration into a connector gap results in a wavelength period change, the ratio of which coincides with the refractive index of water regardless of the size of the gap.<<ETX>>