Understanding BIDI (Bi-Directional) transceivers

BiDi transceivers is short for Bi-Directional Optical Transceiver.

The key-point of BIDI transceivers is that a single fiber.used for both receiving and transmuting data.

In order to distinguish the receiving and transiting data, they must be transmitted using different wavelength. Then Wavelength Division Multiplexing (WDM) couplers is needed to combine and separate data transmitted over a single fiber based on  the wavelengths of the light. Based on this, BIDI transceivers are also referred to as WDM transceivers.

Example:

• Transceiver A’s diplexer must have a receiving wavelength of 1490nm and a transmit wavelength of 1310nm
• Transceiver B’s diplexer must have a receiving wavelength of 1310nm and a transmit wavelength of 1490n

Advantage of BIDI transceivers: require less fiber. 

While BiDi transceivers (a.k.a. WDM transceivers) cost more to initially purchase than traditional two-fiber transceivers, they utilize half the amount of fiber per unit of distance. For many networks, the cost savings of utilizing less fiber is enough to more than offset the higher purchase price of BiDi transceivers.