Differences Between Dual Fiber SFP and Simplex SFP Modules

Dual fiber SFP and simplex SFP modules are two different SFP types, and understanding their differences is crucial for making informed decisions in network deployments. This article explores the nuances between these two fiber optic transceivers, shedding light on their unique characteristics and applications.

Dual Fiber SFP vs Simplex SFP Module: What are They?

Dual fiber SFP modules are the commonly used 1G SFP module type. They operate on a bidirectional transmission mechanism and have two distinct channels or ports for transmission and reception of data. One is transmitting port, and the other one is receiving port. Both transmitting and receiving need one optical fiber to connect. 850nm, 1310nm, 1550nm are the common wavelengths of 1G dual fiber modules.

Simplex SFP modules, also known as BIDI transceiver, employs a unidirectional transmission mechanism and have only one port. This fiber port utilizes a single fiber for both transmitting and receiving, which makes simplex SFP modules a cost-effective solution in scenarios where fiber resources are limited. The wavelength range of simplex SFP fiber module varies between 1300 and 1600 nm.

Dual Fiber SFP vs Simplex SFP Module: What are Their Differences?

Although both dual fiber SFP and simplex SFP modules are used to convert electrical signals to light signals, they differ in several ways, including transmission distance, fiber utilization, and use methods.

Transmission Distance

1G SFP common optical transceiver module uses single mode and multimode fibers to transmit data. With multimode fibers, a 1G SFP transceiver delivers data up to 2km, while single mode SFP transceiver can reach up to 160km.

For BIDI simplex SFP transceiver, this SFP type also works with OS2 cables or multimode fiber cables. And the transmission distance generally ranges from 2km to 120km.

Fiber Utilization

As mentioned above, dual fiber SFP transceiver adopts a duplex interface (now normally LC ports), so two fiber connections are required at least.

Simplex SFP modules excel in efficiently using a single fiber for bidirectional communication. This is particularly advantageous in situations where optimizing fiber resources is a priority. If you have a six-strand fiber you would be able to use all six strands rather than three for one direction and three for the other. This means you can use fewer fiber patch cords and patch panel ports, and decrease the amount of space dedicated to fiber management. With that, it brings more savings.

Used in Pairs

Dual 1G SFP fiber module operates at 850nm, 1310nm, and 1550nm wavelengths. All SFP transceivers must be used by pairs. For common SFPs, we should connect the two SFPs which have the same wavelength together. For example, we use an 850nm SFP at one end, then we must use an 850nm SFP on the other end (shown in the figure below).

For BiDi SFP, they must be deployed in matched pairs like the common SFP transceiver modules. But note that, we should connect the two BiDi SFPs which have the opposite wavelength together. Common wavelengths of simplex BIDI fiber SFP modules are TX1310/RX1550nm, TX1550/RX1310nm, TX1490/RX1550nm, TX1550/RX1490nm, TX1310nm/Rx1490nm and TX1490nm/Rx1310nm. If we use a TX1310/RX1550nm BiDi SFP at one end, then we must use a TX1550/RX1310nm BiDi SFP on the other end.

Conclusion

Common dual fiber SFP modules use two fibers for data delivery while BIDI transceivers employ one fiber for transmission. After a clear understanding of their nuances in transmission distance, fiber utilization, and use methods, you also have to consider your cost and future-proof networking requirements to ensure the right selection.