The invention relates to a WDM-PON (
wavelength division
multiplexing-
passive optical network) for performing OTDR (optical
time domain reflectometry) test without influencing service, and the
system comprises an OLT (optical line terminal) and ONU (
optical network unit), which are connected with each other through an
optical fiber distribution network circuit, a waveband C defined in DWDM (dense
wavelength division
multiplexing) is bi-directionally adopted between the OLT and the ONU as a working
wavelength band, OTDR adopts a
wave band L defined in DWDM as a working
wavelength band, an AWG (
arrayed waveguide grating) in the
optical fiber distribution network circuit is periodic and can work simultaneously in the waveband C and the waveband L; a C / L WDM device in the
optical fiber distribution network circuit completes complexing and division of optical signals of two working wavelength bands in the WDM-PON
system and the OTDRR. The WDM-PON
system for performing the OTDR test without influencing the service is simple and feasible, low in cost, high in reliability and easy to popularize. Due to the adoption of the WDM-PON system, the OTDR test can be conducted by a
passive optical network system under the condition that the user service is not interrupted, and the OTDR reflected optical
signal of each
branch distribution optical
fiber is free from being overlapped on
time domain at the receiving moment of OTDR in the OTDR test.