400G will be the direction for the next generation of backbone network upgrades and new construction, and it will become an inevitable trend in data center development.
What is a 400G Optical Module? #
A 400G optical module is primarily used for photoelectric conversion. An electrical signal is converted into an optical signal at the transmitting end, transmitted through an optical fiber, and then converted back into an electrical signal at the receiving end. The 400G optical module has a transmission rate of 400G and was created to adapt to the network market’s evolution from 100M, 1G, 25G, 40G, to 100G, 400G, and even 1T. The 400G optical module plays a crucial role and has a significant impact on building 400G network systems.
What are the standards and packaging forms of 400G optical modules? There are six main standards and packaging forms:
OSFP #
The full name of OSFP is Octal Small Formfactor Pluggable. This standard is a new interface standard that is not compatible with existing optical and electrical interfaces. Its dimensions are 100.4 × 22.58 × 13 mm³, which is slightly larger than the QSFP-DD and requires a larger PCB area. The pins of the electrical interface are different from QSFP-DD, with a row on both the top and bottom.
QSFP-DD #
The full name of QSFP-DD is Quad Small Form Factor Pluggable-Double Density. This solution is an extension of the QSFP interface, adding a row to the original 4-channel interface to increase it to 8 channels, hence the “double density.” This solution is compatible with the QSFP solution, which is one of its main advantages. The original QSFP28 modules can still be used simply by plugging them into a different module.
CFP8 #
CFP8 is an extension of the CFP4, with the number of channels increased to 8. The dimensions are correspondingly increased to 40 × 102 × 9.5 mm³. This solution has a higher cost, requiring 16 25G lasers.
CWDM8 #
This standard is an extension of the CWDM4 standard, with a rate of 50G per wavelength, which can also reach 400G. Four new center wavelengths have been added: 1351/1371/1391/1411nm. 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.
CDFP #
The CDFP standard was created earlier, and the third edition of the specification has been released. It uses 16 channels, with a single-channel rate of 25G. Due to the large number of channels, the size is also relatively large.
COBO #
The full name of COBO is 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, since it does not support hot-swapping, it will be difficult to repair if a module fails.
At OFC 2018, manufacturers introduced QSFP-DD and OSFP at the exhibition. The advantages of these two solutions are the most prominent. However, which specific solution will be used in the future also depends on the network architecture of the next-generation cloud computing operators.
What is the Purpose of a 400G Optical Module? #
The main function of a 400G optical module is to increase data throughput and maximize the bandwidth and port density of data centers. The future trend for 400G optical modules is to achieve wide gain, low noise, miniaturization, and integration, and to provide high-quality optical communication modules for the next generation of wireless networks and hyperscale data centers.
How many chips are needed for a 400G Optical Module? #
Although only one optical chip is used in a 400G optical module, the cost is high. In 10G/25G optical modules, the optical chip cost accounts for about 30%; in 40G/100G optical modules, it accounts for about 50%; and in 400G optical modules, the optical chip cost is as high as 70%.
What is the difference between 400G optical modules and 10G, 25G, and 40G optical modules? #
Although 10G, 25G, 40G, and even 100G optical modules have become the market mainstream, as the demand for bandwidth, port density, and system energy consumption continues to increase, 400G optical modules will further push technology to a higher level of development.
Compared to 10G, 25G, and 40G optical modules, the arrival of 400G optical modules will usher in a new era for optical communication. Optical communication is transitioning from single-carrier modulation coherent detection in low-end optical modules to polarization multiplexing multi-carrier applications.
Photonic and electronic integration, as well as ADC/DSP technology, will be key to the commercialization of 400G optical communication modules and systems. With the urgent demand for Ethernet standardization, the need for optical parallelization will greatly promote the development of photonic integration technology.
What is the Market Value of 400G Optical Modules? #
As we all know, 100G technology products are already mature, and 400G is a hot topic of discussion. The industry is very concerned about the progress of 400G optical modules. Currently, the progress of 400G optical module development and mass production is relatively satisfactory. In the current market context, the demand for bandwidth in hyperscale data centers is growing, and 400G optical communication modules have become the best choice for improving system performance and reducing bandwidth costs. The advent of 5G networks will be another positive factor driving the market value of 400G optical modules.