| 摘要 |
PURPOSE: To improve linearity in an optical communication system, and to reduce distortion. CONSTITUTION: In an optical signal system 10, one part of an optical output from a light emitter 20 is detected, an electric feedback signal 32 is obtained, the first part of the feedback signal 32 is phase inverted against an electric input signal 14, this is degenerated and synthesized with the electric input signal 14, and a synthetic signal for the AC modulation of the light emitter 20 is obtained. Also, the second part of the feedback signal 32 is time-averaged, and used for controlling DC drive to the light emitter, and it is preferable that the mean light output can be made substantially constant. The above operation is implemented by a modulator 12. Also, the light emitter 20 is controlled so as not to be operated beyond a heat specification and a power specification by a feedback signal 21. Then, distortion introduced in another method to the optical signal system due to non-linearity related with the light emitter driven by a high power level can be reduced. |
