US Patent 7848645 Identifying or locating waveguides

The location or identification of a waveguide is determined, in particular where a disturbance is applied to the optical waveguide. This is achieved by: (a) monitoring the waveguide at a first location to sense a disturbance along the waveguide; (b) causing a disturbance to the waveguide at a second location; (c) transmitting a sensor signal to the second location; and (d) inferring, from the sensor signal, the presence or identity of the waveguide at the second location.