A new fault-identification method using a dichroic reflective optical filter in optical subscriber loops

Abstract

A new method is studied which can automatically identify faults between an optical line and the transmission equipment on the subscriber side. This method employs a 13/1.55-pm-WDM dichroic reflective optical filter and a 1.55-pm-band OTDR. The filter is inserted between the optical line and the transmission equipment. The level and distance of reflection from the filter are measured with a 1.55-pm-band OTDR from the central office in this fault identification method. The required characteristics and structural design method for the filter are discussed. A prototype of the filter is fabricated and which achieves the target characteristics and reliability. System evaluation experiments are carried out and the possibility of 100% fault identification is confirmed as a result of accuracy tests in the field.

New monitoring concepts for optical access networks

“…One simple approach is to insert a reflective element at the end of the fiber link [5]. But this method requires a high resolution OTDR device to separate between fiber links with near equal fiber length.…”

Optical layer monitoring in Passive Optical Networks (PONs): A review

“…Utilization of reflectors in the end of branches (not shown in the Fig. 2a) eases the fault detection process by checking the presence and the height of the end reflection peak for the branch in test [9]. Active by-pass solution has been successfully implemented and deployed by NTT Japan in the automatic fiber line testing system called AURORA [10] and its extensions [11] where the by-passed branching devices are located in the central office.…”