The growth of artificial intelligence infrastructures is driving architectures in which optical links are being integrated with GPUs, processors, and network ASICs. In CPO systems, photonic components are placed alongside integrated circuits to reduce the length of electrical connections and meet the increasing demands for bandwidth, density, and energy efficiency.
This approach, however, introduces new requirements for the fiber itself. The limited space available necessitates the use of very small bend radii and short internal links, conditions under which bend-resistant fibers can be affected by phenomena such as multipath interference (MPI).
Reduced multipath interference on links shorter than two meters
CPO FlexConnect has been specifically developed for this scenario. According to Corning, the new fiber exhibits better bend resistance than its SMF-28 Ultra fiber and is designed to reduce MPI penalties when used in links shorter than two meters.
The fiber has a modal field diameter (MFD) of 9.2 ± 0.4 µm at 1310 nm. This value aims to promote compatibility in optical coupling and minimize insertion losses, two parameters that are especially relevant in connections between fibers and photonic integrated circuits (PICs).
The solution is designed to work in the wavelength range between 1260 and 1360 nm, corresponding to the O band, and has a specified maximum attenuation of 0.5 dB/km at 1310 nm.
Designed for bend radii less than 10 mm
Resistance to optical losses caused by bending is another key feature of CPO FlexConnect. This fiber is designed for deployments requiring radii smaller than 10 mm, a common scenario when numerous optical links need to be integrated in very confined spaces.
In the characterization provided by Corning, the macrobending loss at 1310 nm is 0.025 dB per revolution with a mandrel radius of 10 mm and 0.1 dB per revolution when the radius decreases to 7.5 mm.
In addition, the fiber geometry is controlled. CPO FlexConnect features a cladding outer diameter of 125 ± 0.7 µm, a coating outer diameter of 242 ± 5 µm, and a core-to-cladding concentricity of 0.5 µm or less.
Corning also uses its OVD (Outside Vapor Deposition) manufacturing process, which aims to provide consistency and uniformity in the fiber's properties.
Optical fiber for the interior of CPO systems
The anticipated applications include short-distance single-mode links within Co-Packaged Optics systems, deployments requiring bend radii of less than 10 mm, and single-mode fiber pigtails used in optical components.
The company presented CPO FlexConnect as part of its solutions for new optical infrastructures in data centers. In this type of architecture, optics are no longer limited to the pluggable modules located on the front of the equipment, but are now integrated into ASICs and other processing circuits.
This transition is especially important given the increase in traffic generated by artificial intelligence applications. CPO architectures aim to reduce the distance traveled by high-speed electrical signals using copper and bring electro-optical conversion closer to the chip.
CPO FlexConnect addresses a specific part of this challenge: maintaining optical performance when fibers have to travel very short distances and make sharp bends within equipment with a high component density.
With its combination of bend resistance, reduced multipath interference, and a modal field diameter of 9.2 µm, Corning's new fiber is designed as a connecting element for the next generation of switches, accelerators, and co-packaged optics-based processing systems.
