BRANCHED LIGHT LINE WITH OPTICAL PULSE-TESTING FUNCTION

摘要

PROBLEM TO BE SOLVED: To individually test respective downstream-side optical fibers in a branched light line network by a method wherein a light branching means, an optical pulse testing means and a reflected light filter are provided, wavelength light, for communication, from the upstream side is passed to the downstream side, intrinsic wavelength light for maintenance is passed through optical fibers which are allocated individually in advance and light other than them is cut off. SOLUTION: Wavelength light, for maintenance, which is sent out from an optical pulse testing means 8 is incident on an upstream-side optical fiber 1 via a signal-light input/output means 9. Then, the light is distributed equally into (n) pieces of dowastream-side optical fibers 201 to 206 by a wavelength-independent light branching element 3. The wavelength of beams of branched wavelength light for maintenance is sorted by respective optical band-pass filters 501 to 506, and only the wavelength light which agrees with transmission bands of the filters 501 to 506 is passed. The light is reflected by an optical band-pass filter 60, with a reflection function, which is installed immediately in front of a subscriber terminal 701, it is changed into returned light together with light generated in an optical fiber 1 or the optical fiber 201, and it is propagated in a route in the reverse direction so as to be incident on the testing means 8.