A Beginner Guide: What is 400G Optical Module?

NADDOD Jason Dec 29, 2022

The continued growth in demand for data centers and cloud computing resources has driven the development of hyperscale public cloud data centers. Global data traffic continues to climb, prompting data centers to move from 100G to higher speed, greater bandwidth and lower latency. 400G will be the next generation of backbone network upgrades and new builds, becoming an inevitable trend for data centers. Many service providers have already started to deploy 400G network construction solutions. In the process of building a 400G network system, 400G optical modules play a vital role, so what is a 400G optical module? What is the difference with 10G, 25G and 40G optical modules?

400G Optical Module

What is 400G optical module?

400G optical module, also known as 400G optical transceiver module, is mainly used for photoelectric conversion, converting electrical signals into optics at the transmitting end, and then transmitting them through optical fibres, and then converting the optical signals into electrical signals at the receiving end. The 400G optical module plays a vital role in the construction of 400G network systems.

What are the 400G optical module standards and packaging forms?

The 400G module standard has not yet been unified. There are six main types of 400G optical module standards and packaging forms as follows.

The full name of OSFP is Octal Small Formfactor Pluggable, Octal means 8. This standard is a new interface standard, which is not compatible with the existing optical interface. Its dimensions are 100.422.5813 mm^3, which is slightly larger than QSFP-DD and therefore requires a larger PCB area, and the pins of its electrical interface are different from QSFP-DD, with one row at the top and one at the bottom.

The QSFP-DD, known as Quad Small Form Factor Pluggable-Double Density, is an extension of the QSFP by adding an extra row to the original 4-channel interface to make it 8-channel, also known as double density, and is compatible with the QSFP solution, which is one of the main advantages of this solution. The original QSFP28 module can still be used, simply by inserting another module.

③ CFP8
The CFP8 is an extension of the 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.

This standard is an extension of the CWDM4 standard with a rate of 50G per wavelength, which can also be achieved equally well at 400G. Four new central wavelengths are added, namely 1351/1371/1391/1411 nm. The wavelength range becomes wider, the requirements for Mux/DeMux are higher, and the number of lasers is doubled. The maximum input power is 8.5dBm.

The CDFP standard was created earlier and has now released its third version of the specification. cd stands for 400 (Roman numerals). It uses 16 channels and has a single channel rate of 25 G. Due to the higher number of channels, the size is also larger.

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 is the function of a 400G optical module?

The main function of 400G optical modules is to be able to increase the data throughput, which can maximize the bandwidth and port density of data centers. 400G optical modules future trend is to achieve the role of wide gain, low noise, miniaturization and integration to provide high quality optical communication modules for next generation wireless networks and ultra-large scale data centers.

How many chips are needed for 400G optical modules?

China’s 400G optical module chip import dependence is serious. From the perspective of the global competitive landscape of the optical chip industry, China’s self-sufficiency rate of high-end optical chips with high speed rate as the main feature is insufficient, and the demand for related optical chips is extremely dependent on imports.

Therefore, although the optical chip in the 400G optical module only need to use a piece, but the cost ratio accounted for high, is the optical module industry value chain on the crown jewel. In optical modules, the optical chip occupies the highest value end, and the higher the cost ratio of the optical chip in high-end optical modules, the higher the cost ratio. In 10G/25G optical modules, the cost of the optical chip accounts for about 30%, in 40G/100G optical modules, the cost of the optical chip accounts for about 50%, and in 400G optical modules, the cost of the optical chip accounts for up to 70%.

What is the difference between a 400G optical module and a 10G, 25G or 40G optical module?
Although 10G, 25G, 40G and even 100G optical modules have become the mainstream of the market, with the increasing requirements for bandwidth, port density and the amount of energy consumed by the system, 400G optical modules will be another new stage that can further drive the technology towards a higher speed system.

Compared with 10G, 25G and 40G optical modules, the arrival of 400G optical modules will enable optical communications to enter a new era where optical communications are changing from single-carrier modulated coherent detection of low-end optical modules to polarisation multiplexing of multiple carriers with electro-planar phase modulation and array coherent detection. Photonic integration and electronic integration, ADC/DSP technology will be key to the commercialisation of 400G optical communication modules as well as systems. With the urgent need for Ethernet standardisation, the requirement for optical parallelisation will give a huge boost to photonic integration technology.

What is the market value of 400G optical modules?

As we all know, 100G technology products have matured, 400G is the current hot topic of discussion, and the industry is very concerned about the progress of 400G optical modules. Nowadays, the progress of 400G optical module development and mass production is also more satisfactory. In the current market context, the increasing demand for bandwidth in super-scale data centers, 400G optical communication modules have become the best choice to enhance system performance and reduce bandwidth costs, and with the arrival of 5G networks in the later years, it will be another positive driving factor for the market value of 400 optical modules.

Related Resources:
400G Optical Transceiver Module Types
Typical Solutions for 400G Data Center
Typical Connection Solutions of 400G Optical Transceivers and Cables
The Next Station of Data Center Networks—200G vs 400G
400G Optical Module Application Scenarios
100G & 400G Optical Transceiver Marketing
Four Types of Typical 400G Network Solution Plan Explained
400G Solutions Changes High-Bandwidth DCI Architecture
400G QSFP-DD FR4 vs 400G QSFP-DD FR8
FAQs for 400G Transceivers and Cables