How Much Do You Know About BiDi Transceiver?

In today’s data center, higher bandwidth and larger capacity are required, which, to some degree,  brings about the increasing in the use of optic fiber cables. It’s known that two fiber cables are usually used in the process of data transmission, in which one is for transmitting data, and another one is for receiving data. After that, the cost in the fiber deployment of infrastructure is also increased with it. To solve this issue, BiDi transceiver（Bidirectional transceiver） comes out, such as BiDi SFP, BiDi SFP+, BiDi QSFP+ and so on. Then this article will have an introduction to BiDi transceiver.

What’s BiDi Transceiver?
BiDi transceiver is a kind of bidirectional fiber optic transceiver with single fiber, which transmits and receives different central wavelengths from two different directions by WDM tech, to realize bidirectional transmission of optical signal in one optic fiber. Different from common fiber optic transceiver with two ports, BiDi transceiver is only with one port. It filters wavelength via filter and simultaneously complete the transmission of 1310nm optic signal and receiving of 1550nm optical signal so that it need to be applied in pair. Usually, its wavelength consists of these types: 1310nm/1550nm; 1310nm/1490nm; 1510nm/1590nm.

Types of BiDi Transceiver
The common types of BiDi transceivers include the following ones:

1. BiDi SFP transceiver is typically applied for the high-performance integrated duplex data link on one optic fiber. It interfaces mother board of network device (such as a switch, router or similar device) to a optic fiber or unshielded twisted pair networking cable. In addition, the typical wavelength combination of it is 1310/1490nm, 1310/1550 nm, 1490/1550 nm and 1510/1570 nm. This SFP BiDi transceiver is used in both telecommunication and data bidirectional communications applications.
2. BiDi SFP+ transceiver is an enhanced SFP transceiver. It is designed for bi-directional 10G serial optical data communications such as IEEE 802.3ae 10GBASE-BX by using 1330/1270nm transmitter and 1270/1330nm receiver. And its transmission distance is up to 20 km.
3. BiDi QSFP+ transceiver is designed for high-density data center. With QSFP+ BiDi transceiver, 40G network can be achieved by the exiting 10G cabling. That is to say, if one wants to upgrade his 10G network to 40G network, there is no need to change the existing 10G duplex patch cords into MTP/MPO multifiber patch cords.
4. BiDi X2 transceivers, mainly used in Ethernet network, are designed for bi-directional 10G serial optical data communications, similar to BiDi SFP+ transceivers. The transceiver consists of two sections: the transmitter section and the receiver section. The transmitter section uses a multiple quantum well 1330/1270nm DFB laser. The receiver section uses an integrated 1270/1330nm detector preamplifier (IDP) mounted in an optical header and a limiting post-amplifier IC. This BiDi transceiver is mainly used in Ethernet network.

Advantages of BiDi Transceivers
On the one hand, due to that BiDi transceivers( also called as WDM transceivers) are able to reduce the number of fiber patch panel ports and the amount of tray space for fiber management, as well as to require less fiber cables, the adoption of BiDi transceivers is beneficial to save the cost in fiber cabling infrastructure. Meanwhile, it also makes it possible to save more precious space in data centers.
On the other hand, although the cost of BiDi transceivers are higher than that of common transceivers in the market, and BiDi transceivers utilize half the amount of fiber per unit of distance. For many networks, the saved costs can offset the higher purchase costs of BiDi transceivers. The deployment of BiDi transceivers instantly doubles the bandwidth capacity of the existing optical fiber infrastructure and helps customers to achieve economical and efficient performance for their fiber optic network. Besides, 40G connectivity becomes more reliable via BiDi transceiver.

How Does BiDi Transceiver Work?
Different from traditional optic fiber transceiver modules with two fibers, BiDi transceivers are equipped with Wavelength Division Multiplexing (WDM) couplers, also called as diplexers, which combine and separate data transmitted over a single fiber according to  the wavelengths efficiency. On account of this, BiDi transceivers are also referred to as WDM transceivers.
Furthermore, BiDi transceivers must be deployed in pairs to reach the efficiency, with their diplexers tuned to match the expected wavelength of the transmitter and receiver. For example, paired BiDi transceivers are used to connect device A (Upstream) and device B (Downstream), then the figures are shown as below:

1. Transceiver A’s diplexer must have a receiving wavelength of 1490nm and a transmit wavelength of 1310nm
2. Transceiver B’s diplexer must have a receiving wavelength of 1310nm and a transmit wavelength of 1490nm

 

Conclusion
BiDi transceiver may have a higher cost than common transceivers. However, if seen from a long-term view, it will decrease the costs spent in fiber cables to a large extent. BiDi transceiver is compatible with many data rates.


Note: article resource from http://www.gigalight.com/.