BIDI means Bidirectional, BIDI transceiver processes data in both directions (transmit and receive) through a single optical fiber. As we all know that most optical transceivers have two ports and need two fibers to transmit data, one is to receive data from networking equipment, the other is to transmit data to the networking equipment. But BIDI transceiver have only one port and use one optical fiber to achieve it.
BIDI work principle:
BIDI transceiver usually used in pairs. We know it transmit and receive wavelength in one port at the same time filtered out the other wavelengths, so we need another transceiver to receive and transmit it. For example, the transmitted wavelength is 1310nm and received is 1550nm, so the other transceiver must be transmitted 1550nm and received 1310nm.
Please see the picture below: