Sumitomo Chemical and Kyushu University Demonstrate High Optical Modulation Efficiency and Ultrafast Operation at 180 Gbaud Using KNN Thin-Film Wafers in Optical Modulators

Sep. 28, 2026

Sumitomo Chemical Co., Ltd.
Kyushu University

Sumitomo Chemical Co., Ltd. (“Sumitomo Chemical”) and Kyushu University jointly verified the potential of using potassium sodium niobate (KNN) as a core material in optical modulators for photonics-electronics convergence ^(*1), particularly co-packaged optics (CPO) ^(*2). Their collaboration demonstrated high optical modulation efficiency and ultrafast operation at 180 Gbaud ^(*3). These results show that KNN is a promising material for next-generation photonics-electronics convergence devices.

With the widespread adoption of generative AI, there is growing demand for data processing that is faster and capable of handling larger volumes of data across a wide range of fields. For AI data centers in particular, which handle enormous amounts of information, power consumption and information processing loads have become major global challenges. Photonic-electronic convergence technologies are attracting attention as a key solution to these problems. Among such technologies, optical modulators, which convert electrical signals into optical signals, are garnering interest as essential devices for optical interconnects, including CPO. Currently used silicon-based optical modulators, on the other hand, face challenges in achieving both high-speed operation and low power consumption. Due to this, there is strong demand for next-generation materials that can overcome these limitations.

To address these challenges, Sumitomo Chemical and a research group led by Professor Shiyoshi Yokoyama of the Institute for Materials Chemistry and Engineering at Kyushu University worked together. They focused on the fact that KNN has excellent electro-optic properties and features suitable for optical modulators. Sumitomo Chemical produced KNN thin-film wafers, while Kyushu University was responsible for the design, fabrication, and performance evaluation of optical modulator devices using those wafers. As a result, the optical modulator using the KNN thin-film wafer demonstrated ultrafast operation at 180 Gbaud and achieved a VπL ^(*4) value—an index indicating modulation efficiency—of less than 0.7 Vcm. This represents approximately three times ^(*5) the modulation efficiency of optical modulators using thin-film lithium niobate (TFLN) ^(*6), which is being actively researched and developed as a next-generation optical modulator material, demonstrating the potential advantage of KNN.

In addition to its high performance as an optical modulator material, KNN can also be formed into thin films by sputtering and is highly compatible with existing semiconductor manufacturing processes. Another major advantage is that it is expected to be manufacturable at a lower cost than TFLN wafers. Sumitomo Chemical has manufacturing technologies for mass production, cultivated through its work on piezoelectric MEMS ^(*7) applications, which gives it an advantage in terms of manufacturability as it moves toward practical application of KNN.

These research results were accepted as a post-deadline paper ^(*8) at the 52nd European Conference on Optical Communications (ECOC 2026), held in Spain. ECOC is one of Europe’s largest international conferences on optical communication technologies.

Based on these achievements, Sumitomo Chemical and Kyushu University will further accelerate their work on optical modulators using KNN thin-film wafers with the aim of bringing these devices into practical use.

Sumitomo Chemical will continue to actively promote the increase of new applications for KNN. At the same time, it will also work to contribute to the achievement of a sustainable society through the development of ICT technologies.

Kyushu University is a university that drives societal transformation through integrated knowledge. As such, it will continue to bring together diverse knowledge and human resources and take on challenges toward solving societal issues and transforming societal and economic systems.

(*1) A next-generation semiconductor/data center technology that integrates electrical and optical circuits, replacing electrical signal transmission with light to enable high-speed, large-capacity data communications while reducing power consumption.
(*2) A packaging technology that integrates electrical and optical circuits into a single package. By shortening electrical wiring between chips, it prevents signal degradation and enables low-power, high-speed, large-capacity data processing.
(*3) An important performance metric indicating data transmission speed; it represents how many times per second symbols (signal states) can be switched. 180 Gbaud equates to 180 billion symbol transitions per second.
(*4) A performance indicator showing how efficiently an optical modulator can modulate light. The smaller the value, the lower the voltage required for efficient modulation, and the greater the potential for miniaturization.
(*5) Compared to the representative VπL value of optical modulators using TFLN that is widely reported in published research (VπL = approximately 2.0 Vcm).
(*6) TFLN is an acronym of thin-film lithium niobate, a material under active research and development as a next-generation optical modulator material.
(*7) MEMS is an acronym of Micro Electro Mechanical Systems, a device technology that integrates minute mechanical structures and electrical circuits using semiconductor microfabrication techniques.
(*8) A presentation category for the latest and most important research results obtained up until shortly before an international conference. Acceptance rates are generally low, with especially novel and highly significant results selected.

Reference

Post-deadline paper:
S. Yokoyama, H. Sato, G.-W. Lu, T. Okachi, K. Funahashi, K. Watanabe, M. Shimizu, and Y. Tanaka “180-GBaud OOK Modulation Using a KNN Crystal-Based Electro-Optic Waveguide Modulator” in Proceedings of 52nd European Conference on Optical Communications, Málaga, Spain, 2026, PDP-B-6.

Inquiries

Corporate Communications Department, Sumitomo Chemical Co., Ltd.
https://www.sumitomo-chem.co.jp/contact/public/

Public Relations Office, Kyushu University
koho@jimu.kyushu-u.ac.jp