| 摘要 |
PURPOSE:To obtain a polarization control method capable of suppressing waveform deterioration due to the polarization dispersion of a transmission line in an optical communication system. CONSTITUTION:Signal light 2 frequency-modulated by a frequency f0 is made incident on an optical fiber after passing through a first polarization control element 4. The signal light 2 is separated to two beams of polarization intersecting orthogonally by a polarization separation element 13 after passing through a second polarization control element 12. Polarization-separated signal light are received by a balancing type light receiver, and are converted into electrical signals, and an intensity signal 18 with component of frequency f0 out of the signals is detected. The second polarization control element 12 is controlled so as to always maximize the intensity signal 18, and also, the first polarization control element 4 is controlled so as to always minimize the intensity signal 18. The waveform deterioration due to the polarization dispersion can be suppressed by performing such polarization control. |
