What is a 400G Optical Transceiver?

NADDOD Jason Data Center Architect May 18, 2023


Due to the rapid expansion of mobile internet, cloud computing, high performance computing, AI, big data, and other technologies, the worldwide network traffic is expanding. As a result, major switch vendors in the market have launched ultra-high-speed 400G and 800G switches that support different 400G ports with optical transceivers and cables. Hyperscale public cloud data centers are being developed to meet the growing demand for data centers and cloud computing resources.

In response, data centers are upgrading to 400G network systems, with many service providers already deploying 400G network construction solutions. This beginner’s guide aims to help understand the 400G optical transceiver and its advantages, types, applications, and challenges.

What is a 400G optical transceiver?

The 400G optical transceiver, also known as the 400G optical module or 400G optical transceiver module, serves the purpose of photoelectric conversion. It transforms electrical signals into optical signals at the transmitting end, which are then transmitted through optical fibers. These optical signals are converted back into electrical signals at the receiving end.

The 400G optical module was developed to cater to the network market’s growing demand for increased transmission rates from 100M, 1G, 25G, and 40G, to 100G, 400G, 800G, and even 1.6T.

In building a 400G network system, 400G optical modules play a crucial role in ensuring optimal performance. It can be divided into categories based on optical wavelength, signal modulation mode, transmission distance, and form factor:

● In terms of optical wavelength, it can be divided into multi-mode (MM) and single-mode (SM);

● In terms of signal modulation mode, it can be divided into NRZ and PAM4 modulation (mainly PAM4 at present);

● In terms of transmission distance, it can be divided into 400G SR8, 400G DR4, 400G FR4, 400G LR4, and 400G ZR; 

● In terms of form factor, it can be divided into OSFP, QSFP-DD, CFP8, COBO…etc.

40g 100g 400g Ports Shipments

What are the advantages of deploying a 400G Network?

Higher Bandwidth

400G optical transceivers provide higher bandwidth than their predecessors, allowing for faster and more efficient data transmission.

Higher Transmission Density

For instance, let’s consider the NVIDIA 100G switch SN2700/3700C, which has a port density of 32* 100G/1U. In comparison, the 400G switch SN4700 has 32* 400G QSFP-DD ports in a 1U panel, which offers a port density that is four times higher at the same height.

Faster Speeds

With data rates up to 400Gbps, 400G transceivers can support high-speed data transmission, which is especially useful for applications that require real-time data processing and analysis.

Lower Power Consumption

One of the primary concerns for data centers is to minimize transmission energy consumption. In this regard, 400G is a more energy-efficient option than 100G, as it consumes less energy per unit of information transmission. This not only meets the need for energy conservation but also aligns with the growing emphasis on environmental protection.


Typically, 100G QSFP28 ports support two transmission modes: 100G to 100G and 100G to 4X25G. However, the NVIDIA SN4700 400G switch offers a wider range of transmission modes, including 400G to 400G, 400G to 2X200G, 400G to 4X100G, 400G to 8X50G, and more. This feature allows the switch to cater to various network architectures, making it a versatile option for data centers.

SN4700 Splitting Option

What are the different types of transceivers for 400G?


The QSFP-DD (Quad Small Form Factor Pluggable-Double Density), is an enhanced version of the QSFP interface that expands the original 4-channel interface to 8 channels, doubling its density. This solution is designed to be compatible with the QSFP solution, allowing it to be used with existing QSFP28 modules by simply inserting another module.

The QSFP-DD optical transceiver offers an electrical interface with 8 channels, with each channel having a rate of up to 25Gb/s (NRZ modulation) or 50Gb/s (PAM4 modulation), providing solutions up to 200G or 400G. Its bandwidth can be up to ten times that of QSFP+ or four times that of QSFP28.

The 400G QSFP-DD optical module comes in different form factors, including 400G QSFP-DD DR4, 400G QDD FR4, 400G QDD LR4, and 400G QSFP-DD SR8. The 400G SR8 transceiver meets the IEEE 802.3cm standard and can transmit up to 70m OM3 and 100m OM4/OM5 links. It uses 16-core multimode MPO connectors, with 8 transmitters and 8 receivers, and carries a 50Gbps signal when each channel is modulated by PAM4. The 400G SR8 also has a price advantage as it uses a VCSEL laser. 

400G QSFP-DD SR8 Transceiver
The 400G QSFP-DD is smaller in size compared to the 400G OSFP and It can only support up to 400Gb/s, while OSFP can support up to 800Gb/s. QSFP-DD is intended for the current 400G networks that will be widely deployed, while OSFP is more suitable for future 800G networks. Therefore, considering the current situation, QSFP-DD is more appropriate for the 400G network.


OSFP, which stands for Octal Small Formfactor Pluggable, is a new interface standard that is incompatible with existing optoelectronic interfaces. The name “Octal” refers to its 8-channel interface. It is larger than QSFP-DD, measuring 100.4* 22.58* 13mm, due to it requiring more PCB space. The electrical interface of 400G OSFP is different from that of 400G QSFP-DD, with a row on both the top and bottom for better heat dissipation.


The 400G CFP8 is an extension of the 400G CFP4, with an increased number of channels to 8 and a correspondingly larger size of 401029.5 mm^3, which is the highest-cost solution available.


The 400G COBO stands for Consortium for on board optics, which means that all optical components are placed on the PCB. The main advantages of this solution are good heat dissipation and small size. However, as it is not hot-swappable, it can be difficult to service if a module fails.

At OFC 2018, both QSFP-DD and OSFP were launched by vendors at the show. The two solutions have the most prominent advantages and are most likely to be used as the standard for 400G solutions in next-generation data centers, but in combination with the other standards and packaging forms mentioned above, which solution is used in the future will also depend on the network architecture of the future generation of cloud operators.

What scenarios can 400G optical modules be used in?

400G Application

High Performance Computing (HPC)

The use of 400G optical transceivers in HPC applications has been gaining traction due to their high bandwidth capabilities and low latency. In particular, they are used in InfiniBand and Ethernet applications to improve the performance of HPC systems. We have compiled some information on Benefits of 400G Optical Transceivers for HPC.

For InfiniBand, 400G transceivers are used to connect high-performance computing clusters, storage systems, and other components. These transceivers provide high bandwidth and low latency connectivity, which is essential for data-intensive workloads such as scientific simulations, machine learning, and big data analytics.

Similarly, in 400G Ethernet applications, the 400G transceivers help to connect data centers, servers, and storage systems. They provide high-speed, low-latency connectivity between these systems, enabling faster data processing and improved application performance.

Data Centers and Cloud Computing

With the rise of cloud computing and big data analytics, there is a need for fast and reliable communication between servers and storage devices. Data centers are often distributed across multiple locations, and there is a need for high-speed interconnects between them to transfer data. 400G optical modules can provide the required bandwidth and low latency for these applications.

Artificial Intelligence (AI) & Machine Learning (ML)

400G transceiver enables high-speed data transfer within data centers, making it possible to move large amounts of data between servers and storage devices quickly and efficiently. This is particularly important in AI and ML applications, where the processing of large datasets in real time is necessary. With a 400G transceiver, AI and ML systems can operate at faster speeds and process larger datasets, leading to more accurate results and better insights.

Meta or Metaverse

400G optical transceiver can apply in transmitting high-quality and low-latency data for virtual and augmented reality experiences. These applications require high-speed and low-latency data transmission to ensure that the virtual or augmented reality experience is smooth and without any lag.

Telecommunications Networks & Carriers

For telecommunications companies and carriers, they can use the 400G module to deliver high-speed data and voice services to their customers.

Video Broadcasting & Streaming

400G optical module features the capability to support high-quality, high-bandwidth video transmission in video broadcasting and streaming.

Internet of Things (IoT) Connectivity

The IoT relies on fast and efficient data transmission to connect devices and process data, making the 400G optics a key component in IoT networks.

Medical Imaging and Diagnostics

Medical imaging and diagnostic applications require high-speed data transmission to process and analyze large amounts of medical data, making the 400G optical transceiver a useful tool in this field.

Military and Defense Communications

Military and defense organizations use the 400G optical module to support high-speed and secure data transmission in critical communications applications.

Aerospace and Aviation Networks

Aerospace and aviation industries rely on fast and efficient data transmission for communication and control systems, making the 400G optics an important component in these networks.

Overall, a 400G optical transceiver has the potential to make a significant impact on various industries and applications by providing faster and more efficient data transmission, improving performance, and enhancing the user experience.

What are the challenges associated with 400G transceivers?

High Cost

The manufacturing of 400G modules requires more advanced technology than low-speed transceivers, and therefore their cost is relatively high, correspondingly making them cost prohibitive in some applications.

At NADDOD, large factory qualification ensures that we have the resources and capacity to deliver high-quality products in a timely manner. Therefore, you can enjoy superb cost performance and price advantage with the original comparison and other 3rd party markets.


The production of 400G transceivers is complex, and the manufacturing process requires high precision and quality control to ensure reliability and performance.

NADDOD is a professional provider of innovative optical networking solutions to HPC, networking, data center, and telecom customers and one of TOP10 global transceiver manufacturers. Before we were marketed under the NADDOD brand, we have been focusing on R&D and manufacturing, and have a large number of OEM partnerships with leading communication network companies. While constantly meeting the strict head technical standard, we also continue to invest in independent innovation. Through more than 20 years of accumulated experience in production, we have realized the transformation of OEM-ODM-OBM-NADDOD!


Existing equipment may not be compatible with a 400G module, particularly in cases where multiple vendors are involved.
NADDOD supports compatibility with over 140 vendors. Each product is 100% tested in host devices on site in our labs. Our portfolio is growing to support the ever-increasing need for quality compatibles.

Testing and Validation

There is a need for rigorous testing and validation of 400G optical transceivers to ensure their reliability and performance, which can be time-consuming and expensive. But now you have a chance to apply for a free trial for one month at NADDOD.

Power Consumption

High-speed data transmission requires more power, leading to increased power consumption and heat dissipation, which can affect the reliability and lifespan of the transceiver. However, the max power consumption of NADDOD’s 400G QSFP-DD-SR8 is less than 10W.


The 100G transceiver modules have already matured, and the industry is now focusing on the development of 400G technology. The progress of 400G optical transceiver development and mass production is currently satisfactory. Due to the increasing demand for bandwidth in ultra-large-scale data centers, it has become the best solution to enhance system performance and reduce bandwidth costs. The emergence of 5G networks is expected to further drive the market value of 400G transceivers. The development prospects of 400G optical modules are vast, and they will provide better data transmission speed and energy consumption in the future.

As a world 8th-ranked optical communication products provider, NADDOD provides a range of items such as fiber optic transceivers, fiber optic patch cords and DAC & AOC cables, and other networking series. For those interested in 400G optical transceivers, NADDOD has 400G DR4/FR4/LR4/SR8/ZR optical transceivers with ample stock. NADDOD welcomes you to contact us for more information.

Related Products:
400G QDD FR4
400G QDD LR4
100G QSFP28

Related Resources:
400G Optical Transceiver Module Types
Typical Connection Solutions of 400G Optical Transceivers and Cables
The Next Station of Data Center Networks—200G vs 400G
Four Types of Typical 400G Network Solution Plan Explained
FAQs for 400G Transceivers and Cables