| 摘要 |
PURPOSE:To attain highly stable optical modulation on a transitional basis and on a long-term basis by providing two amplifiers which separately amplify a bias current and a modulation current and a switch circuit which switches the modulation current at high speed and controlling the fluctuation of optical output owing to transitional temperature change. CONSTITUTION:The title device consists of a highly precise and high speed amplifier 5 amplifying a signal converted into an electric signal in a sensor part, a holding circuit 6 storing a voltage corresponding to light intensity at the time of natural light emission, a holding circuit 7 storing a signal correspond ing to intense light outputted from a laser 3 when the modulation current is turned on, a generation circuit 8 for two reference voltages which are to be set as the reference of two-kinds of holding signals, two amplifiers 9 and 10 amplifying the reference voltages and a holding voltage error and outputting the bias current and a modulation current value signal and an ECL circuit switching the modulation current at high speed. Then, both the bias current and the modulation current are controlled for the change of a current-to-optical output characteristic. Thus, highly stable optical modulation is attained on a transitional basis and on a long-term basis. |
