Patent ID: 7242775

Claim:
A method of generating calibrated optical pulses in a quantum key distribution (QKD) system, comprising: sending first optical pulses having a fixed pulse width and a fixed power through a variable optical attenuator (VOA) for different VOA settings, and relating respective transmitted powers of the first optical pulses to respective said VOA settings; setting the VOA to a minimum attenuation; directing second optical pulses having varying pulse widths through the VOA and relating respective transmitted powers of the second optical pulses to the respective varying pulse widths; determining a first average power required for third optical pulses outputted by a optical radiation source in order to obtain a second average power for each third optical pulse at a receiver of the QKD system; determining a calibrated attenuation setting of the VOA that results in each third optical pulse having the first average power; automatically setting the VOA to the calibrated attenuation setting; and sending the third optical pulses through the VOA to create calibrated optical pulses.