| 摘要 |
PURPOSE:To reduce a rising jitter due to a zero-bias modulation by a simple addition element by forming a rise differentiated signal of a pulse signal to be input to a semiconductor laser, combining the signal with the pulse signal to be input to the laser, and pulse-signal-modulating the laser by the combined signal. CONSTITUTION:A differentiator 3 generates a differentiated signal of an input pulse signal. and is set to a time constant of a minimum pulse width or less by using a CR circuit, an LR circuit, etc. A half-wave rectifier 4 outputs part of the input pulse differentiated signal, and outputs a differentiated signal of a polarity corresponding to the rise of the input pulse. A driver 2 is a drive signal generator of a semiconductor laser, and converts the pulse signal to a signal of a driving level of the laser. When the drive signal responsive to the pulse signal is generated, the output of the rectifier 4 is simultaneously combined and produced. The differentiated signal is combined with the input pulse to drive the laser. Thus, the current width of the rise is increased, shortening of an oscillation delay time due to a zero-bias modulation is facilitated, and a rising jitter due to a pattern effect can be suppressed to a minimum. |
