| 摘要 |
PURPOSE:To obtain a photo signal of high output by a method wherein, in the case of a transmitter consisting of a laser beam source which outputs a photo signal modulated by an input electrode signal and a photo amplifier which amplifies the photo signal outputted from the laser beam source, the signal of information same as the photo signal, to be inputted in said transmitter, is used as an excitation signal of the photo amplifier, and besides, the photo signal and the excitation signal are synchronized each other. CONSTITUTION:A modulation signal is led to a branch circuit by inputting it to an electric signal input terminal 1 and splitted into two equivalent signals, and after one of these signals has been sent to and amplified at the first driving circuit 3, a DC bias current is superposed and applied to a semiconductor laser 4. Then, the photo pulse signal, which is the output of the laser 4, is sent to a combination circuit 5 and outputted to the outside as a photo signal through the intermediary of a photo amplifier 6. At the same time, the other signal which was split in the circuit 2 is added to a driving circuit 7 and brought into the prescribed phase, and the degree of photo modulation is increased by supplying said output to the photo amplifier 6. Thus, the deterioration in the ON- OFF ratio of the pulse signal can be prevented. |
