| 摘要 |
PURPOSE:To realize the distortion compensated optical transmission of high reliability by setting the electrical length of a negative feedback loop or adjusting the phase of an electric signal to be negatively fed back so that the phase of the electric signal to be fed back becomes an opposite phase to intermodulation distortion produced in an electricity-light converter. CONSTITUTION:An optical signal outputted from a laser diode LD9 is inputted to a light-electricity converter 10, and here, a signal level is detected. Then, a bias control circuit 11 compares an electric signal level detected by the light- electricity converter 10 with the electric signal level corresponding to desired average optical power set beforehand, and controls a bias circuit 8 so that the desired average optical power is obtained. Besides, a phase shift circuit 12 changes the phase of the feedback signal so as to cancel the intermodulation distortion produced in LD9, and supplies this signal to an adder 13. Thus, in the adder 13, a signal for reducing or removing the intermodulation distortion is added to the electric signal supplied from an input terminal 14. Accordingly, the optical signal of the desired average optical power is obtained in LD9, and the intermodulation distortion is reduced. |
