| 摘要 |
PURPOSE:To stabilize the working of an optical modulator by giving electrically fune vibrations to the driving signal of the optical modulator at a position containing no address signal and deflecting the micro voltage to both polarities by centering the bias point of the optical modulator with said driving signal to observe the variance of luminous intensity. CONSTITUTION:A modulated signal (f) containing an address signal is applied to a detecting circuit 31, and the circuit 31 delivers an address section signal (g). A gate pulse generating circuit I32 produces a gate pulse signal (h) of width T, and a gate pulse generating circuit 33 produces the 2nd gate pulse signal (i). The signals (h), (i) and (f) are applied to an adder circuit 34. An addition signal (j) is applied to an optical modulator driving amplifier 35, and an optical modulator 8 is deflected to both polarities by the micro voltage DELTAV by centering a bias point to produce the variance to the luminous intensity. This light beam is detected by an optical detector 12. Analog gate circuits 37 and 38 sample the parts corresponding to signals (h) and (i) respectively. Outputs (l) and (m) are applied to the amplifier 35 via a differential amplifier 39 and then undergo synchronous wave detection by the signal (j). With such a loop, the working of the modulator 8 is stabilized. |
