Summary form only given. Cost reduction and mass production of optical modules are essential requirements for the realization of optical subscriber access network systems keeping high-speed bi-directional digital fiber communication performance, which are expected by the coming multimedia generation. In this paper, plastic optical modules applying technologies, which have been developed in the field of LSIs are proposed. They are passive surface mountings on Si sub-mounts for bare components and plastic packagings. These technologies lead low-cost solution and mass production for the optical communication modules with high performance and high reliability.