Patent ID: 8909054

Claim:
A bi-direction optical sub-assembly, connected to an optical fiber, comprising: a case body, wherein a transmitter, an optical time-domain reflectometer (OTDR) receiver, a bi-direction optical sub-assembly (BOSA) receiver, a wavelength division multiplexing (WDM) optical filter, and a planar lightwave circuit (PLC) are disposed in an inner cavity of the case body, wherein a first optical path and a second optical path are disposed on the PLC, wherein the first optical path and the second optical path cross to form a coupler structure, wherein a first end of the first optical path is connected to the transmitter, and a second end of the first optical path is connected to the WDM optical filter, wherein a first end of the second optical path is connected to the OTDR receiver, wherein a third optical path is further disposed on the PLC, wherein a first end of the third optical path is connected to the optical fiber, and a second end of the third optical path is connected to the second end of the first optical path, wherein the WDM optical filter is connected to the BOSA receiver, wherein the transmitter is configured to transmit a first communication signal or a detection signal, wherein the first communication signal or the detection signal is input from the first end of the first optical path, is output from the second end of the first optical path, enters the second end of the third optical path through reflection of the WDM optical filter, and is input to the optical fiber from the first end of the third optical path, wherein a second communication signal received by the optical fiber is input from the first end of the third optical path, is output from the second end of the third optical path, and is received by the BOSA receiver through transmission of the WDM optical filter, wherein a Fresnel reflection signal returned due to occurrence of Fresnel reflection when the detection signal encounters an obstacle point in the optical fiber is input from the first end of the third optical path, is output from the second end of the third optical path, is input to the second end of the first optical path through reflection of the WDM optical filter, and after being output from the first end of the second optical path, is received by the OTDR receiver, wherein a cutoff optical filter is further disposed between the OTDR receiver and the first end of the second optical path, and wherein the cutoff optical filter is configured to isolate the second communication signal that is not transmitted by the WDM optical filter completely.