Within an intelligent computing center, an inconspicuous optical module is converting electrical signals into optical signals at a speed of 400 billion bits per second, driving the training and inference of artificial intelligence models.

Against the backdrop of the explosive growth in AI computing power demand, intelligent computing centers have placed extreme demands on data transmission bandwidth, density, and stability.

High-speed optical modules, as the core components for converting electrical and optical signals, directly determine the efficiency of data center computing power scheduling and are figuratively called the “heart” of the data center network.

The 400G OSFP optical module, with its excellent heat dissipation performance and high-density design, is becoming a key component in the construction of current intelligent computing centers.

Background

As the number of parameters in AI models increases exponentially, the demands on data transmission bandwidth for training and inference have reached unprecedented levels. The speed of data flow within the data center directly restricts the efficiency and cost of AI computing.

According to industry observations, the AI ​​application arms race, represented by ChatGPT, has significantly boosted the demand for high-speed optical communication modules.

In this context, high-speed optical modules have become one of the core bottlenecks in improving computing power efficiency. Traditional optical modules are gradually unable to meet the needs of AI data centers in terms of power consumption, heat dissipation, and port density.

The evolution of network architecture from 100G to 400G, 800G, and even higher speeds has become an irreversible trend.

Technical Routes

400G OSFP optical modules are mainly divided into two technical approaches based on their internal architecture and transmission method: the 8-channel 50G PAM4 scheme and the 4-channel 100G PAM4 scheme.

The first type is a multi-channel parallel scheme based on 8x50G PAM4 modulation. Taking the 400G OSFP SR8 as an example, this module uses 8 parallel optical fiber channels, each with a transmission rate of 50Gbps, using 850nm wavelength VCSEL lasers, and connected through an MTP/MPO-16 connector.

It can transmit up to 100 meters on multimode fiber and is mainly used for short-distance high-speed interconnection within or between adjacent racks in data centers.

The other type is a wavelength division multiplexing scheme based on 4x100G PAM4 modulation. A typical example is the 400G OSFP DR4, which utilizes a silicon photonics technology platform to transmit data over four parallel 1310nm optical channels.

Each channel operates at a rate of 106.25Gbps, achieving a transmission distance of 500 meters over single-mode fiber using an MTP/MPO-12 connector.

The 400G OSFP LR4 goes even further, employing wavelength division multiplexing technology to achieve longer transmission distances of 2 kilometers or even 10 kilometers over single-mode fiber.

Practical Applications

In the actual deployment of intelligent computing centers, the choice of 400G OSFP module type requires comprehensive consideration based on the specific application scenario, transmission distance, and cost budget.

The table below clearly compares the key differences between the three main models, serving as a reference for selection:

The selection strategy differs for different architectural levels of intelligent computing centers. In high-density server clusters within the same scalable unit, multimode fiber and 400G OSFP SR8 modules are preferred due to their lower cost.

In long-distance connection scenarios across data center regions, single-mode fiber paired with 400G OSFP DR4 or LR4 modules provides stable and reliable transmission.

Future Trends

Looking ahead at the evolution of optical module technology, higher density, lower power consumption, and greater intelligence are three clear development directions.

With the continuous growth in AI computing power demand, 400G OSFP is gradually evolving towards 800G and 1.6T. Currently, several leading manufacturers have launched 800G optical modules based on the OSFP package, such as the 800G-2xDR4 OSFP and 800G-2xSR4 OSFP.

These modules not only double the data rate but also support port splitting functionality, increasing deployment flexibility.

Silicon photonics technology is becoming a key way to reduce the power consumption and cost of optical modules. Compared with traditional solutions, the silicon photonics platform can integrate multiple active and passive optoelectronic components on a single chip, resulting in a more compact design and lower power consumption.

When data transmission rates increase to 3.2T or higher, traditional pluggable optical components will face severe challenges in terms of heat dissipation and power consumption.

Co-packaged optics technology, which tightly integrates the optical engine and the switching chip on the same substrate, significantly shortens the electrical signal transmission distance, reduces power consumption, and improves signal integrity, and is considered a solution for next-generation ultra-high-speed interconnects.

Final Words

In the data center server rooms, rows of 400G OSFP optical module indicator lights flash regularly, like the heartbeat of the data center, stable and powerful.

The technical specifications of these modules are constantly being updated: chip manufacturing processes are evolving from 10 nanometers to 7 nanometers and even more advanced processes, and power consumption is decreasing from 12 watts to below 10 watts.

With the maturity of silicon photonics and co-packaged optics technology, the boundaries between optical modules and computing chips will gradually blur, eventually merging into a more efficient computing unit.

The heartbeat of the next-generation data center will be even more efficient and powerful.