The impact of AI on the size and demand for optical fibre connectors

In recent years, artificial intelligence (AI) has evolved from a futuristic concept to a ubiquitous technology. In order to cope with the huge demand for AI, many new data centres are needed. 

The servers in these data centres must be connected via cables and, in order to achieve the highest possible transmission speed, optical fibre connectors are an essential addition to copper-based connectors. The faster and the longer the distance to be bridged, the more suitable optical fibre connections are. The following illustration shows the relationship between the use of electrical and optical data transmission.

Figure 1: Separation between electrical and optical applications measured by distance over data rate [Source: A. V. Krishnamoorthy et al, ‘Progress in Low-Power Switched Optical Interconnects,’ IEEE J. Select. Topics Quantum Electron., vol. 17, no. 2, pp. 357-376, Mar. 2011]

Smaller connectors with more optical fibres per connector increase packing density and efficiency in data centres. This clearly shows that AI directly influences the size of the fibre optic connectors and the number of optical fibres per connector.

Optical fibre connections play a crucial role for the AI infrastructure in data centres. For data processing, extremely large amounts of data must be processed in real time wherever possible. To meet this requirement, fibre optic cables and the associated fibre optic connectors are used. Optical fibre connections enable servers to communicate with each other within a data centre. 

Efficient cable and connector management in large data centres requires connectors with as many fibres and as small dimensions as possible, as well as smaller cables with as many fibres as possible – large data centres can comprise thousands of servers, which require a correspondingly large number of plug connections.

Growing demand for optical fibre connections in data centres

There are several factors driving the increasing demand for optical fibre connections. 

Internet Exchange Point operators like DE-CIX reported a new all-time high of 68 Exabytes of global data traffic handled through their nodes in 2024, marking a 15% increase over 2023. Furthermore, the global datasphere, as forecasted by the International Data Corporation (IDC), is expected to surge to 175 zettabytes by 2025 (The Digitization of the World – From Edge to Core). 

This exponential growth is also fueled by the increasing dominance of mobile internet, which accounted for over 60% of web traffic in early 2025 (Statista), and the proliferation of IoT devices, with an estimated 18.8 billion connected devices globally by the end of 2024 (IoT Analytics/Gartner). All data consistently points to an explosive expansion of data and internet traffic. The higher bandwidth offered by fibre optics is another driver for the increasing demand for corresponding fibre optic connections.

To meet the increasing requirements for real-time processing in data centres, the trend is towards optical data transmission. Modern data centres use considerably more optical fibres than older centres. 

Fibre optic connections are showing a trend towards miniaturisation. For example, there are fibre optic connectors with multi-fibre ferrules to connect several fibres at the same time. There are also optical fibres with smaller diameters. Optical fibre connections are future-proof as there are no bottlenecks in data transmission.

The trend towards lower packing density and multi-fibre connectors

Densification in data centres and the need for faster connections are two of the main drivers for the development of new products in this area. 

One trend is the use of smaller ferrules (connection points), which are installed as close as possible to the GPUs, and the installation of multiple fibres in ferrules.

A ferrule is the connection point for a detachable optical connection. The fibres, which usually have a protective coating around the glass, are glued into ferrules. These ferrules can be plugged into each other without any significant change in performance. The end of the fibre protrudes slightly (in the sub-micrometre range) from the ferrule to ensure physical contact. The alignment must be very precise. A single-mode glass fibre transports the light in a 9 µm thick core, which is surrounded by a 125 µm thick protective cladding. As the cores must touch each other, there are high demands on the exact alignment. The ferrule is responsible for the fine alignment, a coarse alignment is made possible by the surrounding housing. Single-fibre ferrules are typically made of ceramic, multi-fibre ferrules are typically made of polymer.

One option for precise alignment of multiple fibres is the multi-fibre - ferrule(MT – mechanical transfer) used in high-density optical fibre connectors. The MT ferrule carries the fibres for the physical contact in a MPO connector. It has two alignment holes for two pins, a plug/socket design, and between the two alignment holes is a row of micro-holes for the fibres. The size of the holes in this ferrule is accurate to 1 micron. The positioning accuracy is in the single-digit micrometre range. For a long time, the MT ferrule was available for up to 12 fibres in a row but recently, a two-row design has been developed that has already doubled the density. 

Further developments have led to a reduction in the size of the ferrules themselves. These small ferrules also use smaller housings. Older MPO housings with MT ferrules are being replaced by the new MMC connector or the SN-MT connector. The MMC thus belongs to the family of VSFF (Very Small Form Factor) connectors.

The number of fibres has increased from 12 to 32. The 32-fibre design is a two-row design with 16 fibres in each row. In a data centre, for example, 6,336 fibres can be connected to a 1U panel with a 24f MMC connection. With 24f MPO, ‘only’ 1,728 fibres can be used in a 1U panel. The density has increased by a factor of 3.

Other aspects of the optical connection have also become denser. The fibre diameter has been reduced from 250 μm (including coating) to 200 μm, which enables smaller cables. Reducing the diameter by 50 μm may not sound like much, but it means reducing the cross-section by 20%. In addition, the fibre bundle becomes smaller as there is less dead space between the smaller fibres.

 In cables, the fibres are sorted into stacks of 12 fibres to make sorting and installation easier. Cables with up to 3,456 fibres are a challenge to install, but sorting in stacks of 12 fibres makes the process easier. The next step is to use sub-units with 288 fibres each. Another feature of the cable is that the sub-units can be easily separated, making access and installation easier.

The key elements of AI data centres

In order to convert or purpose-build a new data centre for AI applications, the following three parameters must be taken into account: performance, efficiency and scalability. These vectors optimally prepare a data centre for AI applications. The smaller, compact connectors reduce the installation costs, as fewer multi-fibre connectors (MPO or MMC) need to be plugged in instead of single-fibre duplex connectors (LC). 

The modularity of the multifibre connectors makes the transition from 40G network bandwidth to 100G Ethernet considerably easier. While 40G and 100G are the backbone of most general data centre operations today, 400G and 800G represent cutting-edge technology and are specifically deployed to meet the ever-increasing bandwidth demands of advanced AI and HPC applications. Modern hyperscale and cloud data centres use 80-90% fibre optics.

All of these trends enable higher density in data centres and must be considered in development. Today, fibre, cable and connectivity are being developed in parallel rather than sequentially to enable higher density and speed of optical connections.