What Are the Benefits of 400G Optical Transceivers for HPC?

What Are 400G Optical Transceivers？

The 400G optical transceivers are optical module products with transmission rate up to 400Gbps, which are advanced transceivers in the field of high-speed transmission. The current mainstream package type of 400G transceiver module is QSFP-DD (Quad Small Form-factor Pluggable Double Density), which is widely used in high-performance data centers, communication networks, large-scale computing, cloud computing, 400G Ethernet and other fields.

Why 400G Optical Transceiver Modules Are in Mass Adoption？

The first is the rise in demand: open systems, artificial intelligence (AI), machine learning and cloud storage are collectively contributing to the exponential growth in data traffic. As large data centers transition to faster, more scalable infrastructures, high-capacity connectivity is critical to keep up with the growing number of users, devices and applications, and 100G networks are no longer sufficient to meet application demands, with 400G networks coming into being.



Network Traffic Growth

The second is the reduction of cost: Intel founder Gordon Moore proposed Moore’s Law , which predicted that the number of transistors that could be accommodated in an integrated circuit would double every 18 months, supporting the semiconductor industry for more than half a century of glory. The same Moore’s Law exists in the field of optoelectronics, where short-range optical transceiver modules evolve by one generation every four years or so, halving the bit cost and halving the power consumption. At this stage, 400G networking technology is very mature, which can greatly reduce customer procurement costs and operation and maintenance costs.



Moore’s Law

Why the QSFP-DD Package？

In order to achieve higher rates, optical transceiver modules generally use three ways: increase the optical device rate (higher baud rate), increase the number of channels (more lane), and use higher-order modulation technology to reduce the transmission cost per bit. 400G modules have a relatively clear technical route: 8*50G PAM4 signals are used to complete 400G transmission, but a variety of options have emerged in the 400G optical transceiver modules packaging standards: CFP8, OSFP and QSFP-DD, among which QSFP-DD has occupied the 400G optical transceivers market with higher density, lower power consumption and better ecology.



The technical route for optical transceiver modules to increase the rate

What Are the Main 400G Optical Transceiver Modules?

400G QSFP-DD SR8 Optical Transceiver Module

The NADDOD 400G QSFP-DD SR8 optical transceiver is compliant with IEEE 802.3cm protocol and meets the requirements of 70m OM3 and 100m OM4/OM5 transmission links. The 400GE module uses a standard 16 core multimode MPO interface and consists of a optical transceiver component, a VCSEL driver, a transimpedance amplifier (TIA), a PAM4 service chip (oDSP), a controller, and six other components; each 8-channel optical and electrical component is placed in a 400Gb/s QSFP-DD package through a compact engineering design.



Block diagram of 400G QSFP-DD SR8 optical transceiver module

The 400G QSFP-DD SR8 optical transceiver module has 8 channels, each carrying 53.125Gbps signals with PAM4 high-order modulation, and the oDSP inside the module performs clock recovery and signal shaping and conditioning functions.

400G QSFP-DD DR4, 400G QSFP-DD DR4+and 400G QSFP-DD FR4 Optical Transceiver Module

The NADDOD 400G QSFP-DD DR4 , 400G QSFP-DD DR4+/XDR4 and 400G QSFP-DD FR4 optical transceiver modules meet the standard IEEE 802.3bs&802.3cu protocols and adopt platform-based hardware design solutions to meet 500m and 2km transmission link requirements respectively. 400G DR4 and 400G DR4+ modules use a standard 12-core MPO connector and 400G FR4 module uses a standard dual LC connector. The 400GbE optical transceiver mainly consists of optical components for transceiver and transmitter, EML driver, transimpedance amplifier (TIA), PAM4 service chip (oDSP), controller and other six parts. The 400GbE QSFP-DD optical transceiver module design uses a full range of independently developed underlying components, covering an end-to-end vertically integrated solution from the optical chip (EML, PD) to the electrical chip (Driver, TIA, oDSP).



Block diagram of 400G QSFP-DD DR4 and 400G QSFP-DD DR4+ transceiver module

The 400Gb/s QSFP-DD FR4 , 400Gb/s QSFP-DD DR4 and 400Gb/s QSFP-DD DR4+ optical transceiver modules have 4 channels for optical signal, each channel carries 106.25Gbps signal, and 8 channels for electrical signal, each channel carries 53.125Gbps signal, both optical and electrical use PAM4 high order modulation, and the rate conversion is realized by oDSP inside the 400G module, which simultaneously completes clock recovery and signal amplification and conditioning functions. In addition, the 400GbE DR4/DR4+ optical transceiver module is designed for parallel light output, and the 4-channel optical signal adopts the same wavelength design; the 400G FR4 optical transceiver is designed for combined wavelength, and the 4-channel optical signal adopts different wavelengths, and is output by the optical port after the optical wavelength division multiplexer synthesizes 1-channel optical signal. Compared with 100G CWDM4 and 100G PSM4, 400G DR4/DR4+ and 400G FR4 optical transceiver module can achieve higher system transmission rate by increasing the transmission rate of optical and electrical single-channel signals and the number of electrical signal channels at the same time.


Block diagram of 400GE-FR4 QSFP-DD transceiver module

400G QSFP-DD LR8 and 400G QSFP-DD ER8 Optical Modules

The 400G QSFP-DD LR8 , 400G QSFP-DD ER8, 400G QSFP-DD ER8 Lite transceiver modules mainly contains: TOSA, ROSA, EML driver, oDSP, controller, etc. The system block diagram is shown as follows: the module connector receives the 8-way parallel 53.125Gbps PAM4 electrical signals from the single board. The electrical signal is processed by the internal digital signal processing chip (oDSP) of the optical module for adaptive processing, and driven by the driver after amplification of the 8-way semiconductor laser (TOSA), and the 8-way semiconductor laser outputs a stable laser signal, which is then output after MUX combining to achieve 8-way electrical to optical conversion.




Block diagram of 400GE-LR8 QSFP-DD and 400G QSFP-DD ER8 transceiver module

NADDOD 400G Optical Transceiver Models

NADDOD is a leading provider of 400G QSFP-DD and 400G OSFP optical network solutions in the world, with industry-leading R&D, manufacturing and technical service capabilities. We continue to provide innovative, efficient and reliable optical network products, solutions and services to our customers.

Conclusion

In the era of high computing power and the increasing bandwidth demand of hyper-scale data centers, 400G optical communication transceiver modules have become the best choice to enhance system performance and reduce bandwidth cost. NADDOD offers a full range of 400G optical transceiver modules from 100m to 40km, come in QSFP-DD (QDD-400G-SR8-S, QDD-400G-FR4-S, QDD-400G-DR4-S) and OSFP (OSFP-2x200G-FR4, OSFP-400G-DR4, OSFP-400G-SR8) form factors, providing a complete solution for interconnecting 100GbE and 400GbE networks with data centers, which are widely used in various network scenarios such as data center networks, metro integrated bearer networks and high-capacity and long-distance transmission networks.