the present invention utilizes two monitoring and feedback loops to track the performance of the laser output as it relates both to the environmental conditions and the effects that gradual changes in the efficiency slope of the laser performance curve have on the modulation amplitude of the laser . the first control loop operates to monitor the changes in the average power output of the laser resulting from the impact of environmental factors and to apply an adjustment thereby increasing or decreasing the drive current to maintain the average power output of the laser at a constant state . the second control loop operates periodically to determine the slope of the performance curve to determine the operating efficiency of the laser thereby providing feedback necessary to determine the drive current necessary to modulate the laser at a constant extinction ratio .