| 摘要 |
PROBLEM TO BE SOLVED: To sustain the extinction ratio at a high level while the eliminating emission lag by generating a bias signal rising simultaneously with an input signal and a bias signal falling simultaneously with a pulse signal rising with a predetermined time lag and feeding a semiconductor laser with currents corresponding to both signals. SOLUTION: A bias signal rises earlier byΔt than a pulse signal and falls at same timing as a pulse current. The bias signal is fed to a current switch comprising transistors 31a, 31b while the pulse signal is fed a current switch comprising transistors 31c, 31d. Consequently, a bias current corresponding the pulse of bias signal flows into the transistor 31b while a pulse current corresponding to the pulse signal flows into the transistor 31d with a time lagΔt and a drive current having specified waveform is fed to a semiconductor laser. Alternatively, the bias signal may be fed to the base of transistor 31a with the base of transistor 31b being earthed.
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