| 摘要 |
PURPOSE:To prevent the change in a stimulated power of a semiconductor laser element when the frequency of an information signal is changed by applying peak hold to a minimum value of the output of a detector for detecting lighting power and instructing the update of the stored content for each predetermined information signal number. CONSTITUTION:A minimum value of an output of a stimulated power detection detector 2 is detected and stored by a peak hold section 9 at the write of information where the stimulated power of the semiconductor laser element 1 is modulated and the holding signal is used as a reference signal for the stimulated power control section 5 controlling the level of the stimulated power to use a DC reference signal at stimulated power modulation of the stimulated power control section 5. The reference signal is not affected by the fluctuation of the stimulated power density. In addition, the holding content is updated in a time when the modulation period is not longer than the time constant of the peak hold section 9. Thus, the stimulated power is controlled based on the detection holding signal of the peak hold section 9 to prevent fluctuation of the stimulated power even if the information signal frequency is changed. |
