Patent ID: 8195047

Claim:
A cable television optical fiber communication system, comprising: a provider end having an information source supplying equipment; plural user ends, each of the user ends having at least one set-top box served to emit an analog return signal to the information source supplying equipment; and plural optical signal transmission devices, each of the optical signal transmission devices respectively connected to the information source supplying equipment and one of the set-top boxes at the user ends, the optical signal transmission device comprising: bi-directional optical sub-assembly (BOSA) connected to the information source supplying equipment via an optical transmission wire and respectively served to convert a first signal of a laser beam into a first RF signal, and convert the analog return signal into a second signal and emit a laser beam having the second signal towards the information source supplying equipment; a RF receive module respectively connected to the BOSA and the set-top box provided at the user end, and served to process the first RF signal from the BOSA, and transfer the first RF signal to the set-top box at the user end; and a RF return module respectively connected to the BOSA and the set-top box at the user end, the RF return module comprises: a detection unit served to detect whether the analog return signal is generated from the user end; a laser control circuit electrically connected to the BOSA and served to enable or disable the BOSA; and a laser on/off circuit respectively connected to the detection unit and the laser control circuit, wherein when the detection unit detects that one of the user end starts to transfer an analog return signal to the RF return module, the laser on/off circuit drives the laser control circuit to enable the BOSA, when the detection unit detects that the user end stops transferring the analog return signal, the laser on/ff circuit drives the laser control circuit to disable the BOSA.