A non-birefringent optical resin material is composed of a resin material and inorganic fine particle material birefringence sign of which are the same. The ONU further includes an ONU chip coupled to the optical transceiver and configured to communicate with the OLT. The present invention thus resolves the frequently seen shortcomings of NFC circuit component failure because of the high temperature when encapsulating, poor waterproofing, and the main body of the ring being too wide. The play holds the governor spring in a free state during rotation of the control lever from the low-speed position to the high-speed position by a predetermined angle. The method and apparatus facilitate the integration of a variety of field equipments with high-speed data links in a factory environment.