400G ZR coherent transceivers are optical modules designed for high speed, high density transmissions for regional and long haul applications such as data centre interconnects (DCI) or metro networks. Much of the current ZR technology supports transmission speeds between 100Gbps and 400Gbps, with new developments reaching 800Gbps. This meets the bandwidth requirements of modern data centres while minimising latency and power consumption compared to other technologies. Although primarily used in the QSFP-DD form factor, ZR technology is also used in OSFP transceivers. There are two types of pluggable coherent ZR transceivers, ZR and ZR+, which comply with OIF MSA and OpenZR+ MSA standards respectively, ensuring industry wide interoperability in both single and multi-vendor networks.
QSFP-DD ZR optical transceiver
Coherent transceivers use various systems to enable high speed, long range transmission with enhanced efficiency and reliability compared to traditional optical transmission technologies. Coherent detection, advanced modulation formats and Digital Signal Processing (DSP) are used to allow higher data rates and improve error correction and signal recovery, extending the potential reach of the modules. Additionally, coherent technology uses three dimensions of light to encode data; amplitude, phase and polarisation, allowing for transmission of more bits per clock cycle. See our Knowledge Base article to find out more about coherent optics.
QSFP-DD 400G ZR technology is used primarily in Dense Wavelength Division Multiplexing (DWDM) applications, channelling multiple data streams through a single optical fibre at speeds of up to 400Gbps. The QSFP-DD form factor provides a small and efficient interface for high speed optical communication and backward compatibility with QSFP, QSFP28 and QSFP56 transceivers, simplifying upgrades without requiring significant infrastructure changes.
400G ZR Overview
400G ZR transceivers excel in point to point data centre interconnect (DCI) applications between 80 and 120km (with amplification). To maintain signal stability over these distances, Concatenated Forward Error Correction (C-FEC) is used, with amplification technology refreshing the signal between the start and end point. 400Gbps bandwidth speeds are possible through 16-QAM modulation, sending high speed data over a single wavelength using DWDM. These transceivers also offer channelisation options, operating as either a single 400Gbps, or 4x100Gbps interface, allowing for compatibility with 100G systems.
400G ZR+ Overview
QSFP-DD ZR+ transceivers are an enhanced version of the standard ZR with more extensive configuration options to suit the requirements of the network. They support both regional and long haul applications with the capability to reach hundreds, or even thousands of kilometres with multiple amplification points depending on the network design. C-FEC is used in some cases, but to achieve the highest transmission distances, Open Forward Error Correction (O-FEC) is typically used.
Forward Error Correction Technology
ZR+ modules can function at various speeds through different baud rates and modulation configurations:
|
Modulation |
Baud Rate |
Transmission Capacity |
|
QPSK |
~60G |
200G |
|
~30G |
100G |
|
|
8-QAM |
~60G |
300G |
|
~40G |
200G |
|
|
16-QAM |
~60G |
400G |
|
~40G |
200G |
These modules also support a variety of channelisation options of 1x400Gbps, 4x100Gbps, 3x100Gbps, 2x100Gbps and 1x100Gbps making them versatile units for a range of network applications. It is worth noting that as the speed setting decreases, the potential range increases and less power is consumed.
400G ZR and ZR+ benefits
In December 2023, Coherent Corp. announced the introduction of the first 800G ZR/ZR+ transceivers in QSFP-DD and OSFP form factors. As the industry accelerates to meet the growing demands of AI, machine learning and cloud computing, companies continue to push the boundaries of data centre speeds. 800Gbps transmission will soon be the industry standard for data centre interconnects as the technology pushes towards 1.6T, while ZR and ZR+ transceivers remain at the forefront of innovation for both long haul and regional applications.
The ability of these transceivers to support speeds of 100Gbps, 400Gbps and now 800Gbps ensures both backward compatibility with previous technology and functionality with the high speed requirements of newer infrastructure designs. Although they can operate without amplification technology, it is necessary to maximise their range. Additionally, these modules eliminate the need for external transponders, reducing maintenance costs, physical space requirements, network complexity, and overall power consumption.
Alongside their performance capabilities, the advanced algorithms and technologies used in 400G ZR transceivers optimise performance and lower power consumption per gigabit transmitted. Internal heat dissipation technology also improves energy efficiency, reducing operating costs and environmental impact. This combination of high performance and sustainability makes the 400G ZR a leading solution for modern data centres.
ATGBICS Solutions
In today’s landscape, the vast majority of data centre and high performance computing applications require data rates of 400Gbps and reliable, powerful interconnects. At ATGBICS, we provide a wide range of products to meet these needs including Direct Attach and Active Optical Cabling and Fibre Optic Transceivers in both QSFP-DD and OSFP form factors. All ATGBICS products are MSA compliant to ensure full compatibility with the OEM part, secured with a lifetime replacement warranty. Our customers benefit from risk free purchasing with our fully tested & uniquely serialised products.
