| 摘要 |
PURPOSE:To prolong the life of an optical transmission device by a method wherein even if the characteristics of a light-emitting element are changed, the optical power of the element is controlled so as to become constant in a state that it is reduced to 3dB or thereabouts of a prescribed value. CONSTITUTION:When a current value of the sum of a bias current and a peak pulse current, which are made to flow through a current drive circuit 5, is inputted in a comparator 7 and the current value is larger than that in a normal case and becomes a second prescribed value or larger to reduce the output beam power of a light-emitting element 1 by 3dB of a first prescribed value, this current value is detected and the amount of attenuation of an optical attenuator 5 is almost made to nil. A voltage which is previously set is applied to an electrical signal from a photodetector 2 by an adder 1, the electrical signal is inputted in an automatic output power controller 4 and the output beam power of the element 1 is controlled so that the sum of the bias current and the peak pulse current of the element 1 is stabilized at the second prescribed value. Thereby, it follows that the error rate of a signal which is received on the side of reception is not reduced to a prescribed value or lower and the life of an optical transmission device can be prolonged. |
