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How AI Computing Boosts 800G Optical Transceiver Development?

Posted on Jan 23, 2024 by
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The booming of large AI models and related applications, has made AI computing power a critical infrastructure for the AI industry. And the development of 800G optical transceiver is crucial for ensuring that the communication infrastructure can manage the rapid data processing and exchange required by AI models.

The Evolution of 800G Optical Transceiver

Increasing Bandwidth Demand

The increase in end-to-end user-facing traffic, driven by AI computing, has resulted in a surge in 800G optical transceiver demand, indicating a greater requirement in the market for improved network bandwidth concurrency and real-time performance. With increasing bandwidth demand, 800 Gbit/s optical transceivers will gradually emerge and are expected to achieve large-scale deployment by 2025, occupying the mainstream market due to their performance advantage.

LPO Technology

The Linear-drive Pluggable Optics (LPO) technology uses a linear drive approach, replacing DSPs with Transimpedance Amplifier (TIA) and DRIVER (drive chip) with high linearity and EQ capabilities. Although DSPs offer functions such as digital clock recovery and dispersion compensation, enabling signal recovery with lower error rates, they also bring higher power consumption and cost.

Compared with traditional solutions, LPO modules use just linear analog components in the data interface, eliminating the need for DSP architecture. So, LPO modules can lower system power consumption and latency by roughly 50% while harming system error rate and transmission distance. This is obviously suitable for short-range, high-bandwidth, low-power, and low-latency data communication in modern Al computing centers.

The 800G Optical Transceiver Classification

There are two main ways to classify the 800G optical transceiver, namely by packaging or the number of channels of the electrical interface. Regarding packaging, there are mainly two types of the 800G optical transceiver including double-density four-channel small form-factor pluggable 800G QSFP-DD and eight-channel small form-factor pluggable 800G OSFP.

If classified according to the number of channels, there are mainly three types:

8×100G PAM4 Optical Transceiver

The PAM4 (Pulse Amplitude Modulation with four levels) modulation allows for the encoding of multiple bits in each symbol, ensuring efficient and high-speed data transmission over optical communication networks.

The 8×100G PAM4 optical transceiver operates using an 8-channel configuration, with each channel carrying a 100G data stream. And there is an instance about 800G XDR8 to 8×100G FR connection with the MTP®-16 APC (Female) to 8 LC UPC duplex breakout cable.

2×400G PAM4 Optical Transceiver

The 2×400G PAM4 optical transceiver utilizes two separate channels, each carrying a 400G data stream. And the following is a connection instance about 800G 2FR4 to 2×400G FR4 with fiber optic patch cables.

800G Coherent Optical Transceiver

The 800G Coherent Optical Transceiver operates on advanced coherent communication principles, modulating amplitude and phase for efficient data transmission. It achieves high data rates through coherent detection and sophisticated modulation formats like QAM.

In practical applications, it functions at 128 Gbd with 16QAM modulation, utilizes four pairs of DACs and ADCs, one laser, and one pair of optical transceivers, and can use a fixed wavelength laser in data center coherent optical modules to decrease cost and power usage.

800G Optical Transceiver Trends in Current Days

According to forecasts, 800G transceivers will gradually emerge and become widely deployed by 2025, taking over the mainstream market due to their better performance. The 800G Ethernet will experience the following three major growth trends in the future:

Single-Mode Optical Interface Solution Migration

Multimode fiber bandwidth restrictions limit the transmission distance of 100G PAM4 VCSEL+ multimode fibers to 50 meters. If OM5 fiber is used, system costs will rise. So, the future will see a shift toward single-mode optical interface solutions, which will benefit SiPh technology.

Arrival of 200 Gbit/s Single-Wavelength

Although 112 Gbd EML technology has advanced rapidly, prototypes have been created, and the 55 GHz bandwidth resources are slightly insufficient. SiPh modulators and silicon-based thin-film lithium niobate have a wide range of applications at 200G PAM4.

The Application Expansion of Coherent Technology Solutions

With improved transmission rates, coherent technology solutions will be able to expand their applications to lower distances such as 40, 20, and 10 kilometers based on an 80 km transmission distance. At the same time, noncoherent solutions are trying to grow over wider distances.

The Impact of AI on 800g Optical Transceiver Deployment

AI servers play a crucial role in supporting large models and AI applications. These servers are specifically designed and optimized to handle the computational demands of complex artificial intelligence tasks. And the deployment of 800G Ethernet is crucial in this process. So why is 800G more pivotal than 400G for AI Servers?

High Data Transfer Rates and Low Latency

AI servers mandate high data transmission rates and low latency, necessitating top-of-rack switches that align with the underlying bandwidth. These switches may additionally require latency redundancy, demanding high-speed optical modules. The GPU servers are designed for intensive machine learning tasks. Generally, each server in a cluster is configured with 4× high-performance GPUs. To enable seamless connection and handle data traffic from numerous servers, the cluster's top-of-rack switch ports must support at least 4× 800G to maintain optimal speed and efficiency in data exchange.

Cost Efficiency Advantage

800G optical chips offer superior cost efficiency and economic advantages. They leverage 100G EML chips, as opposed to 200G/400G, which employs 50G optical chips. Calculations unveil that, for the same rate, the cost of a 100G optical chip is 30% lower than that of two 50G optical chips.

So, in the 800G data center solution, FS offers two types of solutions with 800G, including newly built 800G data centers and the upgrade from 400G to 800G. These solutions make full use of the application advantages of the 800g optical transceiver, allowing for large-scale deployments at a reduced cost.

The Era of 800G Optical Transceiver is Coming

In response to the growing demand for faster and more efficient data transfer, the era of 800G optical transceivers has arrived. With exceptional bandwidth capabilities, advances in LPO technology, and highly cost-effective, these transceivers have the potential to transform the AI sector and reinvent data centers. The deployment of 800G optical transceivers takes us closer to realizing the full potential of AI.

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