| 摘要 |
A laser diode control circuit comprises a load portion, a control portion, a bias current circuit portion, and a modulation current circuit portion. The load portion generates a signal V1 which corresponds to a photocurrent corresponding to an amount of light received in a monitoring photodetector for receiving light from a laser light generating portion. The control portion generates first and second control signals V2, V3 from a value Db, a value Dm, an amount of change DeltaDm, and an amount of change DeltaDb. The amount of change DeltaDm is generated using a function f(Db,DeltaDb)=DeltaDm which is defined such that the light emission power and the extinction ratio become constant. The first control signal V2 is generated from DeltaDb and Db in order to modify a bias current Ib, whereas the second control signal V3 is generated from values corresponding to DeltaDm and Dm in order to modify a modulation current Im.
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