| 摘要 |
PURPOSE:To inhibit variation of transmission delays produced by the difference between optical outputs by equalizing variations of optical powers produced when setting laser diodes in array based on the input of a reference level common to pulse current drive circuits. CONSTITUTION:When a common reference level VR2 is inputted into a common control input terminal 11, this input forces modulation control voltage V2+ or -DELTAV2 to turn to V2proportional i2+ or -betaDELTAi2 when the modulation data input signal VD to be inputted into an input terminal 5 indicates logical 'H' level. In the case of logical 'L' level, the aforesaid control voltage turns into V2+ or -DELTAV2 0. The electric current under the voltage flows into a pulse current drive circuit 23 where the optical output power of a laser diode 4 is controlled by the reference level VR2 to be inputted into the common control input terminal 11. This common control input terminal 11 is distributed into a laser diode drive circuit 2-1, a drive circuit 2-2, and a drive circuit 2-N of an E/O array 1. This distribution makes it possible to equalize all the optical output power of a laser diode 4-1, a laser diode 4-2, and a laser diode 4-N. It is, therefore, possible to inhibit the generation of variation of transmission delays caused by the differential optical output power. |
