| 摘要 |
PURPOSE:To attain long range transmission with optical fiber amplification by injecting a carrier component of a signal light lost during transmission due to induced Brillouin scattering to a receiving end so as to compensate the loss thereby reducing the effect of the induced Brillouin scattering. CONSTITUTION:A signal light sent to a receiving end 14 is branched by a photocoupler 15, a signal light outputted to one output terminal 15c is, converted into an electric signal at a sub light detector 18 of a carrier injection section 17 and a residual carrier detection circuit 19 detects the residual carrier component attenuated and left in the sent optical signal. On the other hand, the wavelength of an injection light source 20 is controlled so that a beat frequency between the injected light source wavelength of the injection light source 20 and the residual carrier component is made zero. The injected light of the injection light source 20 is inputted to an input terminal 15d of the photocoupler 15. Thus, the light of non-modulation with the same wavelength as the carrier component lost during transmission through an optical fiber transmission system is compensated for the signal outputted at an output terminal 15b of the photocoupler 15 and the signal light having the same carrier component as that at transmission is inputted to a photodetector 16. |
