AN OPTICAL RECEIVER AND A METHOD OF PROTECTING SUCH A RECEIVER

摘要

A method of protecting an optical receiver (3), which comprises a photodiode (8) and is capable of receiving optical communications signals, against destructive effects caused by strong optical pulses comprises biasing the photodiode (8), when the communications signals are not detected, by a voltage significantly lower than a normal operational voltage. A control signal is modulated from the optical transmitter (5) on the transmitted optical power, and it is detected in the receiver (3) whether this control signal is received. The photodiode (8) is biased again by the normal operational voltage when the control signal is detected. An optical receiver (3) comprises a photodiode (8) which is biased by a normal operational voltage in an operational state. When optical communications signals are not received, the receiver (3) is moreover capable of assuming a safety state in which the photodiode (8) is biased by a voltage significantly lower than the normal operational voltage. In the safety state, the receiver is capable of detecting the presence of an optical signal modulated by a control signal, and of switching to the operational state when the control signal is detected.