Patent ID: 8654804

Claim:
An optical transmitter, comprising: a semiconductor laser diode (LD) configured to generate an optical output responding to a driving current applied thereto; a thermo-electric cooler (TEC) configured to control a temperature of the LD; an LD-Driver configured to provide the driving current to the LD; a TEC-Driver configured to drive the TEC; and a controller including a flag detector, a current determinant, a temperature determinant, and a step calculator, the flag detector detecting a flag to enable the optical output of the optical transmitter, the current determinant setting a first control signal in the LD-Driver, the temperature determinant setting a second control signal in the TEC-Driver, wherein the controller, synchronous with a detection of the flag to enable the optical output by the flag detector, increases the first control signal from a first current level to a first target level during a transition period in stepwise by a number calculated by dividing the transition period by a preset step period by the step calculator triggered by the detection of the flag, and decreases the second control signal from a second current level to a second target level in stepwise by the number.