At the heart of this evolution are 400G Coherent Optics, which integrate optical and electrical components to enable high-speed, long-reach communication. 400G is optical networking technology that can transfer data at speeds of up to 400 gigabits per second on a single optical wavelength. The terms 400G, 400Gbps and 400GE/400Gbe. 400G capacity over a single wavelength technology is suitable for new and expanding network infrastructures, enabling fiber optic networks to handle the ever-heavier burden of increasing data volumes. It is a proprietary. The 400g Quad Small Form-factor Pluggable Double Density (QSFP-DD) transceivers are classified according to their media and reach. Key components of high-speed networking include:.