| 摘要 |
PROBLEM TO BE SOLVED: To provide a laser diode control circuit for controlling with regard to an optical output power and an extinction ratio of a laser light generating section including a semiconductor light emitting element. SOLUTION: The laser diode control circuit comprises a load section 8, a control section 10, a bias current circuit section 16, and a modulated circuit section 18. The load section generates a signal V<SB>1</SB>corresponding to a photocurrent corresponding to a quantity of light received by a photo detector 4 for monitoring which receives light from the laser light generating section 2. The control section 10 generates first and second control signals V<SB>2</SB>and V<SB>3</SB>from a value Db, a value Dm, a changeΔDb, and a changeΔDm. The changeΔDm is generated by a function f(Db,ΔDb)=ΔDm which is so defined that the light emission power and the extinction ratio are constant. The first control signal V<SB>2</SB>is generated fromΔDb and Db to change a bias current Ib, while the second control signal V<SB>3</SB>is generated from values corresponding toΔDm and Dm to change a modulated current Im. COPYRIGHT: (C)2003,JPO
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