Edited by Chance Lai
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As artificial intelligence models become larger and more computationally demanding, the next bottleneck in AI is no longer processing power alone—it is how quickly massive amounts of data can move between chips, servers and entire data centers.

Researchers at National Yang Ming Chiao Tung University (NYCU) and the Hon Hai Research Institute (HHRI) have developed a high-capacity silicon photonic transmitter that combines a quantum-dot comb laser, wavelength-division multiplexing and multicore fiber technologies to increase optical data transmission. The proof-of-concept system achieved an aggregate transmission capacity of 34.132 Tbit/s through a single optical fiber, providing a promising architecture for future AI data centers and co-packaged optics (CPO). The study was published in Optics Express.

Replacing Electrons With Light

The rapid rise of large language models (LLMs) and generative AI has transformed the architecture of modern AI data centers, where thousands—or even tens of thousands—of GPUs work together to train and deploy increasingly sophisticated models. As computing power continues to scale, however, the volume of data exchanged between processors grows even faster. Moving data efficiently has therefore become one of the industry’s greatest engineering challenges.

To overcome this bottleneck, the semiconductor industry has increasingly turned to silicon photonics, which uses light instead of electrical signals to transmit data at much higher speeds. Unlike conventional copper interconnects, which consume more power, generate more heat and suffer greater signal loss over longer distances, optical communication can carry substantially more information with significantly higher energy efficiency. As a result, silicon photonics is widely regarded as one of the key enabling technologies for next-generation AI infrastructure.

The joint NYCU–HHRI research team sought to increase transmission capacity further while reducing the number of optical components required, creating a simpler, more compact and energy-efficient optical transmission architecture.

One Laser, One Fiber, 34.132 Tbit/s

One of the team’s key innovations is the use of an ultra-broadband quantum-dot comb laser. Conventional optical communication systems typically require multiple independent lasers to generate different wavelengths. In contrast, the new transmitter uses a single laser to stably produce 23 distinct optical wavelengths, greatly simplifying the optical architecture.

The system can be likened to a single light source generating 23 independent high-speed optical channels, each capable of carrying data simultaneously without interfering with the others. By replacing multiple lasers with a single light source, the design reduces system complexity while easing challenges related to packaging, thermal management and device control.

Each wavelength employs PAM4 (Pulse Amplitude Modulation 4-level), enabling transmission at 212 Gbit/s while carrying twice as much information as conventional binary modulation within the same bandwidth. The researchers further expanded system capacity by incorporating a seven-core multicore optical fiber. Unlike conventional optical fibers, which contain only a single transmission path, multicore fibers integrate multiple independent cores within one fiber, allowing several data streams to travel simultaneously.