Get ultrafast, low latency Optical Wavelengths
What is 400G?
400G is optical networking technology that can transfer data at speeds of up to 400 gigabits per second on a single optical wavelength. It provides high-capacity bandwidth to support data-hungry use cases such as data centre interconnects, AI, 5G and IoT.
The terms 400G, 400Gbps and 400GE/400Gbe are sometimes used interchangeably, but they’re not the same:
- 400G refers to optical transport that delivers 400Gbps capacity on one wavelength.
- 400Gbps is the data transfer rate of these networks – 400 billion bits every second.
- 400GE or 400GbE (400Gb Ethernet) is an Ethernet standard set by IEEE 802.3bs and used to connect switches, routers and servers at 400Gbps.
How does 400G work?
400G uses advanced modulation techniques to increase the amount of data carried over optical fibre. The technology you use depends on the distance and application:
- For short to medium reach, PAM4 modules are common. PAM4 uses four amplitude levels to double the bits per symbol. This supports 400G over distances ranging from hundreds of metres to several kilometres, depending on the optics and fibre type.
- For metro and long‑haul transport, 400G uses coherent optical Coherent transceivers apply formats such as QPSK or QAM and digital signal processing (DSP) to maintain clear signals over long distances.
As a result, 400G wavelengths can carry one 400GbE service or multiple lower-rate channels, depending on how they're deployed.
400G optical wavelengths
What standards define 400G?
No single standard defines 400G end to end. Instead, it’s based on a set of Ethernet, coherent optical and transport standards that work together. Here are some common standards in use today – a far from exhaustive list.
IEEE 802.3bs defines 400 Gigabit Ethernet (400GbE). It’s the client interface used on routers and switches to deliver 400Gbps services.
For coherent optical connectivity, OIF 400ZR specifies how to carry 400GbE traffic over DWDM fibre for data centre interconnects up to around 120km using amplified links. Building on that, OpenZR+ extends the range for longer metro and regional distances, supporting flexible bandwidths (commonly 100/200/400Gbps) up to several hundred kilometres or more.
To carry these signals reliably across networks, ITU-T G.709 (OTN) defines how client traffic like 400GbE is packaged, combined and monitored end to end, ensuring carrier-grade performance.
Together, these standards make 400G practical, scalable and interoperable across diverse network environments.
What challenges does 400G solve?
Emerging technologies like AI, 5G and IoT are fuelling unprecedented data growth. Coherent optical wavelengths, scalable from 100Gbps to 1.6Tbps, let you scale to meet this ever-growing demand.
Because 400G delivers more capacity per wavelength, you can simplify network design and cut costs. For example, one 400Gbps port costs less per bit than four 100Gbps ports and consumes considerably less power – one of several benefits of 400G.
What are the benefits of 400G wavelengths?
Deploying 400G wavelengths has several potential advantages for your network, including
- High capacity: Bandwidth up to 400Gbps is ideal for core networks supporting 4K video streaming, AI, 5G and IoT.
- Efficiency: Compared to aggregating multiple 100G links, 400G coherent optics reduce capex and use fewer router ports.
- Energy saving: Consolidating traffic reduces power use and cooling needs, cutting your energy bills.
- Scalability: 400G ZR and ZR+ coherent pluggable optics support flexible data rates (100/200/400G) and make it easy to extend DCI and metro networks.
- Simplicity: With fewer ports, interfaces and fibre links for a given capacity, 400G reduces network complexity.
With managed 400G services, your provider operates and monitors the optical layer end to end. So you can scale up to 400G as you grow without the complexity or cost of managing the transport layer.
Who are 400G optical networks suitable for?
Global data demand is rising relentlessly, but not every business needs 400G today. It’s suitable for organisations that need to transmit huge volumes of data with low latency and high reliability.
Here are some industries and sectors that can benefit from 400G right now.
400G optical networks – typical applications
| Industry/sector | Example use case |
| Telecoms providers | Core networks, 5G backhaul and edge networking to support increasingly digital lifestyles |
| Hyperscalers and AI data centres | Data centre interconnect (DCI), cloud computing, and AI inference and training |
| Media companies | Live 4K video streaming and content distribution |
| Financial services | High-frequency trading and real-time transaction processing |
| Manufacturing | Real-time control of industrial operations via the Industrial Internet of Things (IIoT) |
| Healthcare organisations | Sharing medical images, patient records and research data |
400G optical solutions for your business
If you think 400Gbps optical connectivity might work for you, we can help. At Neos Networks, we design our optical networking solutions to meet your unique business needs now and in the future.
Extend your reach using our high capacity, low latency UK-wide network built for Critical National Infrastructure. With Neos Networks Optical Wavelengths, you get:
- Flexibility: Optical services scalable from 10Gbps to 100Gbps or 400Gbps, with options for multiple services between your sites
- Nationwide availability: Connect from up to 400+ exchanges and 90+ data centres across the UK
- Reliability: Robust, ultra-high bandwidth data transfer using the latest ROADM and DWDM technology with stringent uptime SLAs
- Route diversity: On-net and off-net routing tailored to your business for maximum resilience
- Low latency: Network engineered with the shortest hops for low or ultra-low latency
To find out more and discuss which optical solutions are right for you, get in touch. We’ll be happy to make optical connectivity work for your business.
Get ultrafast, low latency Optical Wavelengths
400G optical networks: FAQs
-
How does 400G internet speed differ from previous networking speeds, like 100G?
400G transfers data at a rate of 400 gigabits per second (Gbps) on a single optical wavelength – four times faster than 100G. -
Can you split 400G into multiple 100Gbps or 200Gbps services?
Yes. Using technologies like OTN multiplexing or flexible coherent optics, a 400G wavelength can carry several 100G or 200G channels. -
What are the main applications or use cases for 400G?
400G is suitable for data-intensive applications that need to transfer huge volumes of data with high reliability and low latency. Typical use cases include data centre interconnects, cloud computing, 4K video streaming, financial trading, 5G backhaul, AI workloads and industrial IoT. -
How does 400G support data centre interconnects?
400G provides ultra-high bandwidth between data centres, enabling fast transfer of massive datasets. Coherent optics and standards like 400ZR+ make it possible to carry 400GbE traffic over long distances, reducing complexity and cost compared to multiple 100G links. -
What are the advantages of 400G optical wavelengths?
400G gives you more capacity per wavelength to support data-heavy workloads like AI, 5G and IoT. It can also simplify your network, cut your cost per bit and lower power consumption. -
Do you need to install new fibre for 400G?
Not necessarily. Our managed Optical Wavelengths service runs over our existing high capacity, UK-wide fibre network using the latest ROADM and DWDM technology. So you can upgrade without major infrastructure changes. We design solutions to make the most of your existing network. -
Can you easily scale up from 100G to 400G?
Yes. Coherent optics and flexible wavelengths let you upgrade from 100G to 400G without replacing your fibre or core infrastructure. With Neos Optical Wavelengths, we handle the underlying DWDM and optical transport network for you, so scaling is simple.
