When servicing data transmission cables, one is often required to be able to distinguish data conduits from each other. For electrical data transmission lines, it is known to utilize unique resistors attached along such conduits to serve as identification markers or labels. This allows service personnel to identify a particular conduit from other adjacent conduits by simply passing an electrical current along the conduit.
However, optical data transmission lines are amenable to such use of electrical resistors as markers. Thus, distinguishing optical conduits from each other remains a difficult task. It is known that an optical time domain reflectometer (OTDR) can be used to identify the time domain reflection signature of light pulses transmitted along an optical data transmission line. Because each optical coupling and other imperfections along an optical line create a reflection, each optical line generally has a unique reflection signature. However, without prior knowledge of the reflection signature of a particular optical conduit, the optical line can not be identified simply by measuring its reflection signature. Moreover, as an optical line is repaired or otherwise altered, its reflection signature changes.
Fiber Bragg Gratings give however a unique possibility to label optical communication lines in a permanent unambiguous way. This can be achieved using Time Domain Encoded labeling: Optical fibers can become labeled by inserting an array of reflective FBG elements with a unique spatial distribution. These labels can become read out using an OTDR equipment. Each label contains a unique set of FBG positions which represent a binary number. Due to the automated Draw Tower Grating process, these type of labels can be produced in a very cost effective way.
For more information about tagging possibilities using DTGs, please contact us.