| 摘要 |
<p>An apparatus (14) for compensation or emulation of PMD effects occurring in an optical signal travelling over an optical fiber based link comprises controllable birefringence sections (15-18) and devices (19-22) for polarization conversion. Each section comprises birefringence optical members or parts thereof and each section is followed or preceded by one of said controllable devices for polarization conversion. The birefringence sections (15-18) are at least three in number and at least one of these has a propagation delay different from that of the other sections. The apparatus comprises a detection device (24) for PMD output and control of controllable devices (19-22) for feedback adjustment thereof so as to keep the detected PMD below a predetermined amount. The apparatus compensates or emulates the PMD effects on a selectable B band. A communication system (10) comprises a transmission apparatus which sends signals to a receiving system (12) by means of a fiber based link (13) with the signal also going through the compensation apparatus (14) as stated above.</p> |
