| 摘要 |
PROBLEM TO BE SOLVED: To measure optical path delay without making test light incident.SOLUTION: In a duplex optical line formed by coupling both ends of a detour optical line 19 to an active optical line 18 connecting an OLT 11 and an ONU 12 via photocouplers 13 and 14, uplink signal light of a first wavelength emitted from the ONU 12 is split into two of the active optical line 18 and the detour optical line 19 by the downstream-side photocoupler 14, the split uplink signal light is converted from the first wavelength to a second wavelength while being propagated in the detour optical line 19 as test light, the test light converted into the second wavelength is multiplexed with the uplink signal light of the first wavelength being demultiplexed and propagated in the active optical line 18 by the upstream-side photocoupler 13, the multiplexed uplink signal light and test light are demultiplexed into an optical signal of the first wavelength and an optical signal of the second wavelength by a WDM coupler 17, a photo current is detected from the optical signals of the wavelengths by photoelectric transducers 113 and 116, and a cross-correlation of two digital signals is analyzed by a correlator 114, thereby measuring optical path delay of the duplex optical line. |
