| 摘要 |
PROBLEM TO BE SOLVED: To attain long range transmission in an optical communication system by changing the polarization state of an optical signal made incident in an optical fiber at a higher speed than that equivalent to a Brillouin scattering response time so as to improve input optical power due to the Brillouin scattering. SOLUTION: A polarization state of an optical signal is changed at a faster speed than that equivalent to a Brillouin scattering response time. In this case, a steady light outputted from a light source 1 is inputted to an intensity modulator 3, in which the light is intensity-modulated by a data signal source 4. The optical signal is given to a polarized wave modulator 11, in which the signal is subject to polarized wave modulation by an electric signal source 12 driving the polarized wave modulator 11 and the modulated signal is sent to an transmission line 5. Furthermore, even when the intensity modulator 3 is replaced with a frequency modulator or a phase modulator, the modulation state is similar. Or the direct modulation system modulating a bias of the light source 1 may be employed. Or when the intensity modulator 3 without any polarization dependency is in use, the arrangement of the polarized wave modulator 11 and the intensity modulator 3 may be reversed. |
