| 摘要 |
PURPOSE:To prevent momentary break of optical communication pulses during the operation of an optical communication device and holds the magnitude of an optical output in a prescribed value, by increasing and reducing continuously currents flowed to one and the other of currents, which flowed to individual semiconductor lasers in each system, respectively while keeping the sum of them constant. CONSTITUTION:The sum of signals S8a and S8b taken out from a differential pair consisting of transistors TRs is constant independently of the magnitude of a switch control signal Sc. When output lights SL1 and SL2 of semiconductor lasers 1 and 10 are synthesized by a synthesizer 9, the synthesized output has the same magnitude as the case where only one semiconductor laser is driven selectively (if degradation of characteristics of semiconductor lasers are ignored). That is, if the magnitude of the switch control input Sc of a switch circuit 8 is changed, not only one semiconductor laser driving circuit is driven selectively and the output light of the selectively driven semiconductor laser is transmitted but also one semiconductor laser is switched to the other and the sum of output lights of semiconductor lasers is kept constant. Even in the switching transient state, the output light without momentary break is transmitted from the synthesizer. |
