| 摘要 |
PURPOSE:To eliminate the conditions by which duty ratios are limited and perform light modulation with correct bias by detecting the duty ratios of input modulating signal and modulating light intensity signal and supplying the ratio difference of both signals to a light modulator. CONSTITUTION:The first duty ratio detector 33 which detects the duty ratio of modulating light intensity signal is constituted by a voltage comparator 31 which compares the input modulating signal from input terminal 2 and a reference signal and outputs a binary voltage signal and a low pass filter 32 which receives the output of said comparator as the first input of a differential amplifier 14. The second duty ratio detector 36 which detects the duty ratio of the input modulating signal is constituted by a voltage comparator 34 which compares the modulating light intensity signal of the output light detector 11 and a reference signal and outputs a binary voltage signal and a low pass filter 35 which receives the output of said comparator as the second input of a differential amplifier 14. Thereby, the light modulation may be accomplished with correct bias. |
