Comprehensive Guide to 400G QSFP-DD Optical Modules: Types, Applications, and Future Trends

The continuous growth in global data traffic has driven data centers to upgrade from 100G to 400G networks. 400G optical modules offer a highly efficient, cost-effective solution to enhance system performance, speed up transmission, broaden bandwidth, and reduce costs. This article introduces the types of 400G QSFP-DD optical modules, their applications, FAQs, and future trends.

Common 400G QSFP-DD Transceiver Types

Generally, there are eight common 400G QSFP-DD transceiver types in the market:

400G QSFP-DD SR8: Ideal for Short-Distance Transmission

The 400G QSFP-DD SR8 is a four-channel, hot-pluggable optical module that supports MMF links up to 70m (OM3) or 100m (OM4) with an MPO-16 connector, making it ideal for short-distance interconnection. It complies with QSFP-DD MSA specification and IEEE 802.3bs protocol and includes eight parallel transceiver lanes, each of which is capable of a transmission rate of 53.125 Gbps (PAM 4), to transmit data rates of 400 Gbps.

400G QSFP-DD DR4: Efficient Mid-Distance Solution

The 400G QSFP-DD DR4 achieves a max transmission distance of 500 meters on 1310nm center wavelength over SMF with an MPO-12 connector. DR4 stands for "Dense Wavelength Division Multiplexing (DWDM) 4-lane", which means that the 400G DR4 module uses four optical lanes to transmit data, each of which is capable of carrying data at a rate of 106.25Gbps (PAM4), reaching a 425G transmission rate.

400G QSFP-DD XDR4: Extended Distance Module

The 400G QSFP-DD XDR4 is an extended version of the 400G QSFP-DD DR4 optical module, of which transmission distance is longer than QSFP-DD DR4, supporting a maximum link up to 10km over SMF with MTP/MPO-12 connector, complying with IEEE 802.3bs protocol and QSFP-DD MSA standard. It has four parallel transceiver lanes, which allow a total transmission rate of 400G.

400G QSFP-DD FR4 and FR8: High-Speed and Long-Distance Options

The 400G QSFP-DD FR4 (Full Duplex 4-lane, Retimed 4-level) is a high-speed, hot-pluggable transceiver supporting up to 2km reach over single-mode fiber (SMF) with duplex LC connectors. It operates with four independent lanes at 100Gbps each using CWDM4 wavelengths, adhering to the 100G Single Lambda MSA specification. With PAM4 modulation, each lane delivers up to 106.25Gbps, totaling a 400G transmission rate, making it ideal for data centers requiring efficient, high-speed connectivity.

The 400G QSFP-DD FR8 module utilizes 50G PAM4 modulation technology similar to the QSFP-DD SR8 but features eight optical lanes for data transmission, achieving a maximum rate of 400Gbps. While the FR8 shares the same modulation technology, it supports longer distances, with a maximum range of 2km, making it suitable for more extended connections in data centers.

400G QSFP-DD LR4 and LR8: Long-Distance High-Speed Solutions

The 400G QSFP-DD LR4 is a high-speed, high-bandwidth, and long-distance transmission transceiver, appropriate for application scenarios like 400G ethernet and data center interoperability. It supports SMF links to 10km over duplex LC connectors and complies with IEEE 802.3bs protocol and QSFP-DD MSA standard.

The 400G QSFP-DD LR8 also adopts 50G PAM4 modulation technology as SR8 and FR8 and has eight parallel transceiver lanes. However, in contrast to SR8 and FR8, each lane allows longer transmission distances of up to 10km over SMF with duplex LC connectors and has a maximum transmission rate of 106.25Gbps, for a total of 425G.

400G QSFP-DD ER8: Best for Ultra-Long-Distance Transmission

The 400G QSFP-DD ER8, with the same technology as the LR8, extends the range to 40km, is ideal for ultra-long-distance applications, and complies with IEEE 802.3cn and QSFP-DD MSA standards.

400G QSFP-DD Optical Modules Application Scenarios

The 400G QSFP-DD optical modules offer a cost-effective and low-power solution for next-generation data centers, metropolitan networks, and long-distance high-capacity transmission. Here’s how they are used in different scenarios:

Data Center Interconnection

In modern data centers, 400G QSFP-DD modules facilitate high-speed connections between servers, switches, and other network devices. These modules enable seamless data interoperability and efficient data transfer, essential for maintaining optimal performance within data centers.

Metropolitan Bearer Network

The rise of cloud computing, big data, ultra-high-definition video, IoT, VR/AR, 5G, and connected vehicles has intensified the demand for high-bandwidth, low-latency, and reliable networks. In metropolitan areas, 400G QSFP-DD modules meet these demands by supporting upgraded core layer bandwidths of 200GE and 400GE, which are crucial for handling the high throughput required by 5G and other advanced applications.

Long-Distance High-Capacity Transmission

400G QSFP-DD modules excel in long-distance transmission by providing high-capacity, flexible, and efficient network solutions. They enable the use of a single 400G wavelength to support extended distances, allowing for adaptable wavelength management, reduced latency, and lower power consumption. This makes them ideal for meeting the increasing demands for bandwidth and network performance in long-haul communication.

For more on 400G network solutions, see FS 400G Product Family Introduction.

FAQs about 400G QSFP-DD Transceivers

Q: Can OSFP and QSFP-DD modules be used together?

A: Yes, as long as both ends of the link use the same Ethernet media type.

Q: Can I plug a QSFP-DD transceiver module into an OSFP port?

A: No. QSFP-DD and OSFP are different form factors. You can use only one kind of form factor in the corresponding system. If you have an OSFP system, then 400G OSFP optics must be used. If you have a QSFP-DD system, then 400G QSFP-DD transceivers must be used.

Q: How do 40/100G optical modules differ from 400G optical modules?

A: 400G optical modules use advanced multi-carrier technology for higher speeds and efficiency, whereas 40/100G modules use simpler single-carrier systems. Although 400G modules come with higher costs and more form factors, they offer greater bandwidth, lower power consumption, and faster speeds.

Q: What is the difference between NRZ and PAM4?

A: NRZ (Non-Return to Zero) uses two signal levels to represent binary data, with one level for "1" and another for "0". It’s common for data rates up to 25Gb/s. PAM4 (Pulse Amplitude Modulation-4) uses four signal levels, allowing it to transmit two bits per level. This means PAM4 can double the data rate compared to NRZ at the same speed.

Q: What are the pros and cons of OSFPs vs. QSFP-DDs?

A: QSFP-DD modules are backward compatible with 40G and 100G QSFPs but require external heatsinks for cooling. OSFP modules have integrated heatsinks for better thermal performance but may need adapters for compatibility with some systems.

400G QSFP-DD Transceiver Future and Trends

The technical advancement of 400G improves the efficiency and capacity of data transmission and brings a better network experience for users. With high bandwidth, low latency, and low power consumption, the 400G QSFP-DD module might be the ideal choice for next-generation wireless networks and ultra-large-scale data centers. Visit FS.com and explore our full range of 400G QSFP-DD optical modules. See how FS can help you meet your high-speed networking needs.