BiDi stands for Bidirectional. Technology that transmits and receives on different wavelengths over a single fiber, reducing fiber usage by half. The term is most useful when a project connects that definition to a concrete use case such as Telecom access, campus, 5G fronthaul.
The reference framework matters when specifying BiDi for Telecom access, campus, 5G fronthaul. The applicable IEEE 802.3, ITU-T, or multi-source agreement defines lane count, wavelength, fiber, reach, and interoperability assumptions. A product name or quotation that mentions BiDi without that context is not yet a complete requirement.
BiDi should not be treated as another name for CWDM. BiDi is defined here as Technology that transmits and receives on different wavelengths over a single fiber, reducing fiber usage by half. By comparison, CWDM means a wavelength multiplexing technology with relatively wide channel spacing that carries multiple signals on one fiber. The two concepts may appear in the same design, but they answer different engineering or purchasing questions.
For a deployable BiDi requirement, record lane count, wavelength plan, fiber type, connector, reach, FEC assumption, and optical power budget. Do not infer those details from DR / DR4 or from a headline speed alone, because the related concept is defined separately as a single-mode parallel-optics standard generally intended for data center links up to 500 m; DR4 uses four optical lanes.
Frequently Asked Questions
How is BiDi different from CWDM?
BiDi refers to Technology that transmits and receives on different wavelengths over a single fiber, reducing fiber usage by half. CWDM instead refers to a wavelength multiplexing technology with relatively wide channel spacing that carries multiple signals on one fiber. They can be related in one project, but one does not prove compliance with the other.
Where is BiDi normally used?
Typical use includes Telecom access, campus, 5G fronthaul. The exact implementation still depends on the host equipment, link design, environment, and governing specification.
What should a BiDi specification include?
It should state lane count, wavelength plan, fiber type, connector, reach, FEC assumption, and optical power budget. These details allow a supplier or engineer to verify the requirement instead of relying only on the term BiDi.
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