In this paper, an all optical wavelength multicasting service in AWG-based WDM PON is introduced, and a novel architecture supporting multiple multicasting groups is proposed. The novel characteristic is that different from the PON systems which broadcast the signals to all the receivers, multicasting signals are only delivered to desired users. This restricted member multicasting brings the trusted security in access network to answer the requirement of high-volume and highvalue contents delivery applications. By employing multiple wavelength selective multicaster (WSM) modules, various multicast groups can be supported simultaneously. Moreover, the capacity of this restricted member multicasting can be extended flexibly according to the increasing multicast requirement.