An Optical Network Unit (ONU) is a critical device in fiber-to-the-home (FTTH) networks, acting as the endpoint that converts optical signals from your ISP into electrical data for your devices. With the rise of high-speed internet, ONUs have evolved into two main types:. Switches and network adapters with SFP modules allow you to create custom high-speed Ethernet networks. For example, using QSFP+ fiber transceiver modules, you could achieve 40 Gbps speeds across a building. Find QSFP+. The optical module serves as a crucial component in optical fiber communication systems, operating at the physical layer, which is the lowest layer in the OSI model. Compared to traditional copper cable access, FTTH offers higher bandwidth, faster transmission speeds, and longer transmission distances.