Basic Terms You Need to Know about 100G Transceiver Optics

Posted on Oct 18, 2023 by

FS 100G QSFP28 Transceiver

The world of networking is evolving at an unprecedented pace, driven by the insatiable demand for faster and more efficient data transmission. This has led to the development and widespread adoption of 100G (100 Gigabit) transceiver optics. These optical modules are critical components in modern data centers and high-speed networks. To understand and navigate this dynamic field, it's essential to be familiar with the basic terms and concepts surrounding 100G transceiver optics.

Basic Terms About 100G Transceiver Optics

Basic Terms About 100G Transceiver Optics


The "100GBASE-SR4" is a common 100G transceiver standard, where "SR" stands for Short Reach. This type of optic is designed for short-distance connections, typically within data centers. It uses multi-mode fiber (MMF) to transmit data up to 70 meters, making it suitable for inter-rack connections and high-density server configurations.


In contrast to SR4, "100GBASE-LR4" is a long-reach transceiver standard. "LR" stands for Long Reach, and it's intended for longer-distance connections. LR4 optics employ single-mode fiber (SMF) to transmit data up to 10 kilometers, making them ideal for connecting data centers within a campus or even across cities.


Similar to LR4, "100GBASE-ER4" (ER stands for Extended Reach) is used for long-distance connections. ER4 optics are designed for even greater distances, with a reach of up to 40 kilometers. These are used in scenarios where data centers need to be connected across a metropolitan area.

100G PSM4

Parallel Single-Mode 4 (PSM4) is a 100G transceiver technology that uses four independent lanes of single-mode fiber. Each lane operates at 25 Gbps, providing a total of 100 Gbps. PSM4 optics are used for medium to long-distance connections and can cover distances of up to 2 kilometers.

100G SWDM4

Short Wavelength Division Multiplexing 4 (SWDM4) is a relatively new technology that allows 100G data transmission over multi-mode fiber. It enables the use of existing MMF infrastructure while providing the higher bandwidth of single-mode fiber. SWDM4 supports transmission distances of up to 150 meters.

100G CWDM4

100G CWDM4 is a technology that multiplexes four different wavelengths onto a single fiber. Each wavelength operates at 25 Gbps, resulting in a total data rate of 100 Gbps. CWDM4 is designed for medium to long-distance connections, with a reach of up to 10 kilometers.

100G 4WDM

100G 4WDM (Four-Wavelength Division Multiplexing) is a technology that uses four wavelengths on a single fiber, similar to CWDM4. However, 4WDM extends the reach to up to 40 kilometers, making it suitable for long-distance connections in data center interconnects.

100G Single Lambda

100G Single Lambda technology, also known as 100G CLR4, leverages a single wavelength to transmit 100 Gbps of data. This simplifies the optical design and reduces power consumption. Single Lambda optics are typically used for short-range connections within data centers and have a reach of up to 2 kilometers.

PAM4 vs. NRZ Modulation

Two common modulation schemes used in 100G transceiver optics are PAM4 (Pulse Amplitude Modulation, 4 levels) and NRZ (Non-Return-to-Zero). PAM4 is more complex but offers the advantage of transmitting more data within a given bandwidth, making it suitable for higher-speed applications. NRZ, on the other hand, is simpler and more robust but offers a lower data rate. The choice between these modulation schemes depends on the specific requirements of the network.

Forward Error Correction

Forward Error Correction (FEC) is a crucial technique in optical communications. It involves adding redundancy to transmitted data, allowing the receiver to detect and correct errors that may occur during transmission. FEC is especially important in high-speed optical networks like 100G, where signal degradation can happen due to various factors, including noise and distortion.

Final Words

Understanding the basic terms and concepts related to 100G transceiver optics is essential for anyone working in the field of networking and data centers. With the constant evolution of technology, staying up-to-date with these terms can help you make informed decisions when choosing the right optics for your specific applications.

As the demand for higher data rates and greater bandwidth continues to grow, the development of even faster and more efficient transceiver optics is inevitable. This will necessitate continued learning and adaptation to new standards and technologies, making it an exciting and dynamic field for networking professionals.

Whether you are an IT manager, a network engineer, or simply someone interested in the world of high-speed data transmission, knowing these fundamental terms will help you navigate the ever-changing landscape of 100G transceiver optics with confidence. So, stay informed, keep learning, and be prepared for the next wave of technological advancements in networking.

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