随着社会的发展，人们对通信服务质量的要求越来越高，除了一般的电话、传真和数据业务外，还要有会议电视、高速率数据传输、电子邮政、电视点播（VOD）等。为了迎接这一多媒体时代的到来，世界各国均在建设信息高速公路，其重点和发展方向已转向光接入网技术。国外在80年代就 With the development of the society, people have higher and higher requirements on the quality of communication services. In addition to the general telephone, fax and data services, there must also be conference television, high-speed data transmission, electronic postal service and VOD. In order to meet the advent of this multimedia era, all countries in the world are building information superhighways, and its emphasis and development direction have shifted to optical access network technologies. Foreign in the 80’s