| 摘要 |
PURPOSE:To obtain the transmitter in which an extinction ratio pulse width in an optical output peak value and an optical waveform is not fluctuated even when a current optical conversion efficiency of a light emitting element 3 is fluctuated. CONSTITUTION:The characteristic of the light emitting element 3 that the optical pulse width is made narrower than the modulation current pulse width by modulating the light emitting element 3 with a bias lower than a threshold level is utilized. The transmitter is provided with a comparator 14 averaging an optical pulse width and detecting the reduction in the optical pulse width as a decreased averaging level, and with a modulation control circuit 15 limiting the increase in the modulation current when the average level starts being lower. The circuit is operated in subordination to the control circuit making an optical output peak constant. |
