Patent ID: 7653102

Claim:
An apparatus for controlling the output power level of a laser, the apparatus comprising: a laser capable of being driven to produce light; a laser driver that generates an electrical bias current signal and an electrical modulation current signal that are used to drive the laser to cause the laser to produce a modulated light beam that is modulated between a logic 0 output power level, P 0 , and a logic 1 output power level, P 1 ; a high-speed laser output power monitoring device that receives a fraction of the light produced by the laser as optical feedback and produces an electrical feedback signal based on the fraction of the light received from the laser, the electrical feedback signal having a first modulation amplitude corresponding to the laser output power level P 0 and having a second modulation amplitude corresponding to the laser output power level P 1 ; a single high-speed amplitude detector that receives the electrical feedback signal produced by the monitoring device and detects the modulation amplitudes of the electrical feedback signal, the amplitude detector producing an optical modulation amplitude (OMA) detection signal corresponding to a difference between the first and second modulation amplitudes of the electrical feedback signal; a high-speed amplitude measurement device that receives the OMA detection signal produced by the single high-speed amplitude detector and produces an OMA amplitude measurement value corresponding to the OMA detection signal; an average amplitude measurement device that also receives the OMA detection signal produced by the single high-speed amplitude detector, the average amplitude measurement device producing an average amplitude measurement value based on the OMA detection signal; and a laser controller that receives the OMA measurement values produced by the high-speed amplitude measurement device and performs a modulation current adjustment algorithm that processes the OMA measurement value and produces a modulation current control signal that is output to the laser driver, and wherein the laser driver receives the modulation current control signal produced by the laser controller and sets an amplitude of the electrical modulation current signal based on the received modulation current control signal, and wherein the laser controller also performs a bias current adjustment algorithm that processes the average amplitude measurement value and produces a bias current control signal that is output to the laser driver, and wherein the laser driver receives the bias current control signal and sets an amplitude of the electrical bias current signal based on the received bias current control signal.