Optical transmitter

A optical transmitter comprising:

• a light emitting device being provided a driving current and for emitting light on the bases of the driving current;
• a light measure for measuring an output light power level of the light emitting device;
• a controller for controlling the driving current to the light emitting device in order to change the measured output light power level into a set output light power level of the light emitting device;
• a current measure for measuring a level of the driving current to the light emitting device;
• an abnormality detector for detecting an aged deterioration of the light emitting device on the bases of the current level of the driving current by the current measure and the measured output light power level by the light measure;
• and
• an adjuster for reducing the set output light power level in the controller when the abnormality detector detects the aged deterioration of the light emitting device.