BiDi Transceiver Overview

BiDi is short for Bidirectional. BiDi transceivers use two different wavelengths to achieve transmission in both directions on just one fiber. General optical module has two ports, TX for the launch port, the RX receive port, as seen in the following picture, while BIDI optical module is only one port filtered by the filter in the optical module, which completes the 1310nm optical signal transmitting and 1550nm optical signal receiver, or vice versa. The most frequently used wavelength of BIDI optical module is 1310nm/1550nm, 1310nm/1490nm, 1510nm/1590nm.

Use of WDM (Wavelength Division Multiplexing) technology, BiDi optical transceiver is a compact optical transceiver module used in optical communications for both telecommunication and data bidirectional communication applications. The transceiver interfaces a network device mother board, like a switch, router or similar device, to a fiber optic pairs or unshielded twisted pair networking cable. In the industry there are several synonyms for Bidi optics, like Bi-directional optics, BX-D/BX-U, WDM and so on. Bidi transceivers can be used in different Gigabit Ethernet applications like 1G, 10G or 40G Ethernet.

BiDi SFP Transceiver

BIDI SFP transceiver module is specifically used for the high-performance integrated duplex data link over a single optical fiber. These transceiver modules are compliant with the SFP Multi-source Agreement (MSA). With the hot pluggability, these modules offer an easy way to be installed into SFP MSA compliant ports at any time without the interruption of the host equipment operating online.

BIDI SFP transceiver module using a long wavelength DFB laser diode enables data transmission up to 80km on a single mode optical fiber. BiDi SFP can be produced either with SC or LC simplex port, that is used both transmission and receiving. The transmitter incorporates a highly reliable 1310nm or 1550nm Laser (FP laser for narrow, Intermediate distance and DFB laser for long distance) and a driver circuit which converts data to light with APC function.

How BiDi Transceivers Work

The most obvious difference between BiDi transceivers and traditional transceivers is that BiDi transceivers are fitted with WDM couplers, which combine and separate data transmitted over a single fiber based on the wavelengths of the light. The figure below depicts the details of how BiDi transceivers work. The two wavelengths that have been used in this example are 1310nm and 1490nm. Usually the upstream transmits at the shorter wavelength, while the downstream the longer wavelength.

Note that BiDi transceivers must be deployed in pairs, with their diplexers tuned to match the expected wavelength of the transmitter and receiver that they will be transmitting data from or to.