| 摘要 |
PURPOSE:To prevent a pattern effect based on the delay of the change of charge density, and to simplify the adjustment of an optical output waveform by making DC bias lower than a threshold value for a period of a low level in ''1'' of an input RZ pulse. CONSTITUTION:When a RZ pulse input signal of a period T is transmitted over a gate G1, an output from the gate is applied to a transistor TR1 as an input 1 as it is. The transistor TR1 and a transistor TR2 are differential-connected to form a current switch, and predetermined collector currents I1 are generated when the level of the input 1 is larger than reference voltage VR applied to the transistor TR2. On the other hand, an inversion output from the gate G1 is delayed only by the half period T/2 of RZ pulses through a delay circuit D, and applied to a transistor TR3 as an input 2 to generate currents I2. Since driving currents ILD to a semiconductor laser LD take a current value IB smaller than a threshold value for a period of a low level immediately after a high level in input pulses ''1'', charges in the semiconductor laser LD disappear for the period. |
