In the field of high-speed data transmission, 100G QSFP28 optical modules have become a key component of network communications. With the continuous expansion of data center scale and the extension of network coverage, how to choose the right optical module - single fiber (BIDI) or multi-fiber , has become an important issue that many network engineers and decision makers need to carefully weigh.

BIDI optical module: Efficient use of optical fiber resources

The core advantage of the single-fiber solution lies in its efficient use of optical fiber resources. In some scenarios where space is limited, optical fiber laying is difficult, or optical fiber resources are scarce, the single-fiber solution demonstrates unique value. It only requires one optical fiber to achieve bidirectional data transmission. Through wavelength division multiplexing (WDM) technology, optical signals of different wavelengths are combined and transmitted in one optical fiber. After reaching the receiving end, the signals of different wavelengths are separated by a demultiplexer.

Taking long-distance transmission as an example, the transmission distance of ETU-Link 100G QSFP28 BIDI optical module can reach up to 40km through single-mode optical fiber OS2 ; this long-distance transmission capability makes the single-fiber solution popular in long-distance communication scenarios such as metropolitan area networks and wide area networks.

However, the single-fiber solution also has some challenges . Since it uses a more complex wavelength division multiplexing technology, the cost of the optical module is relatively high . At the same time, single-fiber bidirectional transmission has more stringent requirements on the quality and performance of the optical fiber. Once the optical fiber fails, it may affect both the sending and receiving of the signal, increasing the difficulty and complexity of maintenance . Moreover, the single-fiber optical module requires the modules at both ends to be strictly paired for use .

Multi-fiber optical modules : A simple and reliable transmission option

multi-fiber solution has a place in many scenarios due to its simplicity and reliability. The multi- fiber solution uses two optical fibers, one for sending signals and the other for receiving signals. This separate transmission method makes signal transmission more stable and reduces the possibility of signal interference.

ETU-Link 100G Multi-Fiber Optical Module

Multi-fiber solution are its lower cost and better compatibility. Due to its relatively simple structure, the manufacturing cost of the multi-fiber optical module is lower and the price is more affordable. Any two multi-fiber optical modules that meet the standards can be connected and used, and do not need to be used in pairs like single-fiber optical modules . The maintenance cost is low, and troubleshooting and repair are easy, reducing business downtime .

How to choose: Comprehensive consideration of multiple factors

In practical applications, when choosing a 100G optical module long-distance solution, multiple factors need to be considered comprehensively. If optical fiber resources are tight and there are high requirements for transmission distance, such as in wide area network construction, the single-fiber solution is undoubtedly a better choice. Although it is more expensive and difficult to maintain, it can meet the needs of long-distance transmission and efficient use of optical fiber resources.

For scenarios that are cost-sensitive, have relatively low transmission distance requirements, and require high system stability and compatibility, such as short-distance connections within enterprise campus networks or data centers, multi-fiber solutions are more suitable. They can not only provide stable and reliable transmission, but also reduce costs and maintenance difficulties.

Single-fiber and multi-fiber solutions each have their own advantages and disadvantages. There is no absolute best solution for the selection of 100G optical module long-distance transmission solutions, only the solution that best suits the specific application scenario.