This paper discusses an optical access system that enables emergency voice communication when a power failure occurs in a user's house, and we also propose a super low power consumption detector that consists entirely of passive devices. And we present applied techniques that comprise sub-carrier multiplexing for user multiplexing/demultiplexing and a new passive detector for signal regeneration driven solely by the transmitted optical signal power. Then we confirm the feasibility of the system experimentally by using a prototype detector that has 8-channel selectivity. We report the realization of the intended detector functions that we achieved by back-to-back simulated voice signal regeneration.