| 摘要 |
PURPOSE:To receive stably an optical signal of burst form incoming periodically without distortion by detecting a mean value of a level of an optical signal incoming periodically at each period and using the mean value to adjust the bias potential of a DC eliminating capacitor to the optical signal received at the next period and the gain of the amplifier. CONSTITUTION:The optical signal PD of burst form is inputted to a photodiode 1 at each period T shown in a figure (a) for times T1-T3 shown in a figure (b) and the optical signal PD is converted into an electric signal by the photodiode 1. Succeedingly, a DA converter 12 converts the mean value of the optical signal at the period just before into an analog signal and the said analog signal is fed to a gain adjusting signal of the amplifier 3. Similarly, the DA converter 13 converts the mean value of the optical signal of the period just before into an analog signal and the said analog signal is fed as a bias potential signal of the capacitor 2 via a resistor 14. For example, the DA converter 12 outputs a gain adjusting signal having a level shown in a figure (e) inversely proportional to the mean value of the optical signal received at the period just before. Thus, the gain of the amplifier 3 is adjusted at each period T to stabilize the output signal. |
