Direct-connected optical cable

Direct connections to optical cables can be achieved using Active Optical Cables (AOCs) or by connecting devices to an Optical Network Terminal (ONT), depending on the application and distance requirements.

Direct Attach Cables (DACs) vs Active Optical Cables (AOCs)

DACs are factory-terminated copper cables with transceivers on each end, providing a direct electrical connection between devices. They are ideal for short-distance connections (typically under 10–15 meters) in data centers, connecting switches, servers, or storage devices. DACs come in passive (no electronics, very low power consumption) and active (with signal-boosting electronics, slightly higher power use) variants . AOCs, on the other hand, use optical fiber to transmit data. They convert electrical signals into light at the source and back into electrical signals at the destination. This allows longer distances (up to 100 meters or more) and higher bandwidth, making them suitable for high-performance computing, cloud infrastructure, and data center interconnects . AOCs are lightweight, immune to electromagnetic interference, and support high-speed applications like 10G, 40G, 100G, and beyond .

Connecting Directly to an ONT

For fiber-optic internet at home or business, the ONT serves as the endpoint of the fiber network, converting optical signals into electrical signals for devices. It typically provides Ethernet ports for direct connection to a computer or router . While it is technically possible to connect a device directly to the ONT, this setup is limited because most ONTs have only one or a few Ethernet ports, restricting the number of devices that can access the network. Direct connection can offer faster and more reliable speeds by bypassing a router, but it should be done with caution and ideally under ISP guidance to avoid service issues .

Key Considerations

• Distance: DACs are cost-effective for short distances; AOCs are better for longer runs.
• Bandwidth: AOCs support higher speeds and are suitable for high-performance applications.
• Power Consumption: Passive DACs consume minimal power (<0.15W), active DACs slightly more, while AOCs require 1–2W due to optical conversion electronics .
• Application: DACs are common in data centers for short interconnects; AOCs are preferred for high-speed, long-distance connections; ONTs are used for fiber-to-the-premises connections. In summary, direct optical connections can be implemented using AOCs for high-speed, longer-distance data transmission or by connecting directly to an ONT for fiber internet access, while DACs remain a cost-effective solution for short-range electrical connections in data centers.