Researchers at Keio University in Japan have achieved a milestone via a plastic optical fiber (POF) technology. The innovative technology could usher in a new era for short-range high-throughput communication at AI data centers.
The technology was announced at the Optical Fiber Communication Conference (OFC) 2025, where researchers unveiled a multicore graded-index POF. The project is led by Professor Yasuhiro Koike and Lecturer Kenta Muramoto at the Keio Photonics Research Institute. Mainly, its purpose is to address infrastructure demands for AI, such as extremely high throughput capacity, minimal latency for GPU connectivity, etc.
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Plastic optical fiber vs traditional AI gears
Traditional fiber setup uses ribbonization and multicore connectors. The fiber is basically glass-made. The researcher’s new method allows for to manufacture of multicore POFs in a single step using extrusion molding. According to the participants, this lowers the cost and complexity in the range of 10 to 100. Through this innovation, multicore fiber can be manufactured in mass, which makes it adaptable to a diverse range of data centers.
In their test, the team achieved a transmission of 106.25 Gbps PAM4 across 30 meters. Likewise, signal integrity was high with minimal degradation in TDECQ, and bit error rates (BER) were reduced by up to 1/10,000 to 1/100,000 compared to conventional glass fibers.
“GI-type POF has a property in which the fine non-uniform structure formed inside the core reduces the coherence of light, functioning as a volumetric noise reduction effect throughout the entire optical fiber,” researchers said.
The multicore GI-POF, which included a 61-core circular version and a 4-core rectangular variant, demonstrated large-scale manufacturing reliability and stable transmission in all cores.
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So far, two papers containing the details of the project have been submitted to OFC 2025. With AI growing more dominant for large use cases, Keio’s multicore plastic fiber technology could unlock a new generation of scalable infrastructures for service providers.