| 摘要 |
PURPOSE:To make the circuit scale small by devising an error amplifier such that positive feedback is applied for high frequency self-oscillation when an optical output of a semiconductor laser is at a prescribed level or over and negative feedback is applied when the optical output of the semiconductor laser is less than a prescribed level. CONSTITUTION:When an input pulse signal is at an H level, an error amplifier 10 is in positive feedback operation and oscillated in itself at a prescribed frequency, resulting that a high frequency signal is used as a drive signal and fed to a laser diode 4, from which a high frequency optical pulse signal is outputted. On the other hand, when the input pulse signal is at an L level, a reference current Iin is decreased, then a drive current of the laser diode 4 decreases below the threshold level Ith. Thus, the error amplifier 10 stops self-oscillation, resulting that the high frequency optical output is not generated from the laser diode 4. Thus, a high frequency oscillator, an amplitude modulator and a current adder are not required, the circuit constitution is simplified more and the size is made small. |
