| 摘要 |
PURPOSE:To prevent the generation of jitter in an optical output signal even in the high speed optical digital transmission by extracting a high frequency signal having a frequency being an integer multiple of the frequency of a signal current or a clock signal from the clock signal of the pulse signal current or the current itself to modulate a semiconductor laser with a current as the result of superimposition of the high frequency signal on the pulse signal current. CONSTITUTION:A transmission signal inputted to a terminal 1 is converted into a drive current signal by a drive circuit 3 and fed to the semiconductor laser 4. On the other hand, the transmission signal or the clock signal inputted to a terminal 2 is inputted to a high frequency extracting circuit 5, from which a high frequency signal having a frequency being an integral number of multiple of the clock frequency is extracted. The high frequency is inputted to the drive circuit 3 and superimposed on the transmission signal to modulate the semiconductor laser 4. In such a case, since the transmission signal and the high frequency signal are synchronized in the drive circuit 3, no jitter is generated in the laser drive current and then no jitter is produced in the optical output waveform. |
