波分复用无源光网络(WDM-PON)实现了点到点的连接，可为每个用户提供专有波长，被普遍认为是未来宽带接入的代表性技术。WDM-PON的关键在于：要求采用低成本、“无色”的光网络单元(ONU)，以避免波长选择器件所带来的安装、运营以及维护成本的增加。本文简要分析了3种WDM-PON的无色ONU的实现方法，指出无色ONU是构建WDM-PON的一种较理想的解决方案。

WDM-PON is commonly believed to be a representative technology for the future broadband access as it enables point-to-point connection and provides each user with a pair of dedicated wavelengths. The key to WDM-PON is adopting low-cost “colorless” ONU, thus avoiding the cost increases in installation, operation and maintenance resulted from wavelength selection devices. This paper presents and briefly analyzes three approaches for colorless ONU implementation for WDM-PON and points out that colorless ONU is an ideal solution for WDM-ONU construction.