| 摘要 |
An optical fibre system, for example a passive optical network having a tree structure, includes at least one optical fibre and is tested at a number of locations (24, 26 and 32 to 35) by a reflectometry method. The system includes a laser for sending light into the system and a detection station for receiving light that has been reflected at the locations at which the system is tested. The laser emits light at a number of different wavelengths ( lambda 42 to lambda 47) that correspond to different resonant modes of the laser, and each location of the system has at least one Bragg grating (51 to 56) that reflects light at one of the wavelengths of the laser. Different locations in the system have different Bragg gratings and/or combinations of Bragg gratings so that each of the locations will generate a reflection that is characteristic of that location. |
