Kyushu University and Sumitomo Chemical demonstrate high optical modulation efficiency and ultrafast operation at 180 Gbaud using KNN thin-film wafers in optical modulators

Fukuoka, Japan—Kyushu University and Sumitomo Chemical Co., Ltd. have verified the potential of using potassium sodium niobate (KNN) as a core material in optical modulators for photonics-electronics convergence. Optical modulators are a next-generation semiconductor/data center technology that integrates electrical and optical circuits that replace electrical signal transmission with light to enable high-speed, large-capacity data communications while reducing power consumption.

The new findings have particular utility in co-packaged optics (CPO), 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. The new technology demonstrated high optical modulation efficiency and ultrafast operation at 180 Gbaud, a performance metric indicating data transmission speed that represents how many times per second symbols, or signal states, can be switched.

These results show KNN as 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, power consumption and information processing loads have become a major global challenge. Photonic-electronic convergence technologies are attracting attention as a key solution to these problems. Among such technologies, optical modulators are garnering interest as essential devices for optical interconnects, including in CPO. Silicon-based optical modulators 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.

The research team 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 designed, fabricated, and conducted performance evaluations. They found that the KNN optical modulator demonstrated ultrafast operation at 180 Gbaud and achieved a VπL value—an index indicating modulation efficiency—of less than 0.7 Vcm. This is almost three times the modulation efficiency of Thin-Film Lithium Niobate (TFLN), another promising next-generation optical modulator.

In addition to its high performance, 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 capability for mass production, cultivated through its work on piezoelectric Micro Electro Mechanical Systems (MEMS).

Sumitomo Chemical and Kyushu University hope to further accelerate their work on these new optical modulators with the aim of bringing these devices into practical use.

These research results were accepted as a post-deadline paper 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.

Post-deadline paper information:
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.

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

Public Relations Initiative, Kyushu University
sysintlkh@jimu.kyushu-u.ac.jp