Sustainable Development Goals

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Author: Emma Stein | Published: May 13, 2026, 14:05

The explosive growth of AI applications is driving ever-increasing data traffic in data centers. Currently, traditional pluggable optical transceivers are widely used as electro-optical conversion components in data centers, but as transmission speeds rise, they generate enormous operating costs due to high power consumption. To address this issue, a research team from National Tsing Hua University successfully developed a “Pulse Amplitude Modulation-4 (PAM-4) transceiver.” By highly integrating optoelectronic components through silicon photonics technology, the new design replaces bulky and power-hungry traditional pluggable modules, effectively shortening signal transmission distances and reducing energy loss.

Traditional AI data centers mainly rely on copper wires as transmission media, but they are now facing bottlenecks such as limited bandwidth, high power consumption, and high latency. As a result, next-generation AI data centers are rapidly shifting toward optical interconnect architectures. Among them, pluggable optical modules are currently the most widely used electro-optical conversion components in Ethernet switches for data centers. These modules can be inserted or removed while equipment is operating, enabling connections between optical fibers and network switches.

The Era of Light-Speed Computing

However, conventional pluggable optical modules are large in size and located relatively far from switch core chips. Signal attenuation during transmission often requires additional circuitry for compensation, significantly increasing operational costs. Consequently, Co-Packaged Optics (CPO) — which directly packages optical chips (for optical signal transmission) and electronic chips (such as logic chips) onto the same substrate — has emerged as a key solution to the high power consumption and transmission latency challenges of the AI computing era. By shortening data transmission distances, CPO can increase transmission speeds while substantially reducing power consumption.

Supported by the “Key Emerging Chip Design R&D Program,” a research team consisting of Associate Professors Peng Peng-Rui and Hsieh Bing-Shiuan from the Department of Electrical Engineering at National Tsing Hua University, Associate Professor Liu Yi-Chun from the Institute of Electronics Engineering, and Dr. Lin Ming-Wei from the Taiwan Semiconductor Research Institute under the National Applied Research Laboratories, successfully integrated a PAM-4 transceiver into a CPO module. The single-channel transmission speed can reach 100 Gb/s, offering the potential to replace traditional pluggable optical conversion architectures while meeting demands for higher transmission speeds and lower power consumption.

Associate Professor Peng explained that the PAM-4 transceiver increases the number of signal amplitude levels from the traditional two levels to four levels, effectively doubling data transmission capacity. However, accurately demodulating four different amplitude levels requires a more complex receiver architecture. To solve this challenge, the team designed an innovative PAM-4 receiver that leverages low-resolution analog-to-digital converters to achieve high-speed data sampling and demodulation.

Challenging Advanced Processes with Mature Manufacturing Technology

One major advantage of this technology is that it achieves performance comparable to international companies’ advanced 7-nanometer processes using a mature 28-nanometer manufacturing process, with power consumption only 10–20% higher. If this architecture is further implemented using advanced process technologies, power consumption could potentially be reduced by half, demonstrating strong industrial competitiveness.

To further shorten the distance between optical and electronic chips, the team also used a 100 Gb/s electrical transceiver chip as the core and adopted flip-chip packaging technology to directly bond the electronic chip upside down onto the optical chip in the CPO module. Compared with traditional pluggable optical modules, the CPO module offers a highly integrated design that shortens system transmission distances, effectively improves bandwidth, and lowers power consumption.

Peng stated that, in addition to industry-academia collaborations, companies are already discussing technology transfer opportunities, and the related technologies are expected to have strong potential for future industrial commercialization.

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