With the continuous growth of demand for data centers and cloud computing resources, it has driven the development of ultra large scale cloud data centers. The continuous growth of global data traffic is driving the development of data centers from 100G to faster, larger bandwidth, and lower latency. 400G will be the direction for upgrading and constructing the next generation backbone network, and will become an inevitable trend in the development of data centers.
Many service providers have started deploying 400G network construction plans, such as Cisco, Huawei, and others. In the process of building a 400G network system, the 400G optical module plays a crucial role. So, what is a 400G optical module? What is the difference between 10G, 25G, and 40G optical modules?
What is a 400G optical module?
The 400G optical module is mainly used for photoelectric conversion. The electrical signal is converted into an optical signal at the transmitting end, and then transmitted through optical fiber. At the receiving end, the optical signal is converted into an electrical signal. The transmission rate of 400G optical module is 400G, which was born to adapt to the network market of 100M, 1G, 25G, 40G to 100G, 400G, and even 1T. The 400G optical module plays a crucial role and influence in building the 400G network system.
What are the standards and packaging forms for 400G optical modules? There are mainly six standards and packaging forms:
OSFP
The full name of OSFP is Octal Small Form Factor Pluggable. This standard is a new interface standard that is not compatible with existing optoelectronic interfaces. Its size is 100.4 * 22.58 * 13 cm³, slightly larger than the size of QSFP-DD, requiring a larger PCB area. The pins of the electrical interface are different from QSFP-DD, with one row at 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 one line from the original 4-channel interface to 8 channels, known as dual density. This solution is compatible with QSFP solutions, which is one of its main advantages. The original QSFP28 module can still be used by simply inserting another module.
CFP8
CFP8 is an extension of CFP4, increasing the number of channels to 8 and correspondingly increasing the size to 40 * 102 * 9.5 mm³. The cost of this solution is relatively high, requiring the use of 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, namely 1351/1371/1391/1411nm. The wavelength range has become wider, with higher requirements for Mux/DeMux, and the number of lasers has doubled, with a maximum input power of 8.5dBm.
CDFP
The CDFP standard was born earlier, and so far, 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 relatively large.
COBO
COBO stands for Consortium for on Board Optics, which means placing all optical components on a PCB. The main advantages of this solution are good heat dissipation and small size. However, due to the lack of support for hot swapping, it will be difficult to repair any module that malfunctions.
What is the function of a 400G optical module?
The main function of the 400G optical module is to improve data throughput and maximize the bandwidth and port density of the data center. The future trend of 400G optical modules is to achieve wide gain, low noise, miniaturization, and integration, and provide high-quality optical communication modules for the next generation of wireless networks and ultra large data centers.
How many chips are needed for a 400G optical module?
Although only one optical chip is used in the 400G optical module, the cost is high. In 10G/25G optical modules, the cost of optical chips accounts for about 30%; In 40G/100G optical modules, the cost of optical chips accounts for about 50%; In the 400G optical module, the cost of the optical chip is as high as 70%.
What is the difference between 400G optical modules and 10G, 25G, 40G optical modules?
Although 10G, 25G, 40G, and even 100G optical modules have become mainstream in the market, with the increasing requirements for bandwidth, port density, and system energy consumption, 400G optical modules will further push technology to a higher level of development.
Compared with 10G, 25G, and 40G optical modules, the arrival of 400G optical modules will usher in a new era of optical communication. Optical communication is transitioning from single carrier modulation coherent detection in low-end optical modules to polarization multiplexed multi carrier applications.
Photon integration, electronic integration, and ADC/DSP technology will become key to the commercialization of 400G optical communication modules and systems. With the urgent need for Ethernet standardization, the demand for optical parallelization will greatly promote the development of photon integration technology.
