An optical communications system includes a plurality of optical fiber spans. An optical loss of one of the plurality of optical fiber spans is different from an optical loss of another one of the plurality of optical fiber spans. At least one of the plurality of optical fiber spans includes an optical...http://www.google.com.tw/patents/US20060193035?utm_source=gb-gplus-share專利 US20060193035 - Optical Amplification System For Variable Span Length WDM Optical Communication Systems
