Yuichi Hasegawa

Addressing social challenges through unique technology

Development of products indispensable for 5G communication ahead of competitors around the world

Mobile phone base station systems support 5G networks, enabling high-speed, large-capacity infocommunications. In such base station systems, GaN (gallium nitride) HEMTs (high electron mobility transistors) have been adopted globally for amplifying radio waves. The Sumitomo Electric Group developed them ahead of competitors around the world.

This is an innovative electronic device that we have developed by leveraging our compound semiconductor technology. The device features the advantage of GaN, instead of conventional silicon. The device achieves high output with less power consumption and less heat generation. Accordingly, the installation of GaN HEMT eliminates the need to use components such as cooling fans within the mobile phone base station, contributing to making the station smaller and lighter. Underpinning the world’s 5G communications networks, this electronic device is expected to play an important role in the coming era of 6G as well.

GaN HEMT and other electronic devices, as well as optical devices and their applications, are handled by the Transmission Devices Division. Sumitomo Electric Device Innovations, Inc. (SEDI), a wholly owned subsidiary of Sumitomo Electric, is in charge of product development and manufacturing.

Development and manufacturing products underpinning DX

On the other hand, typical products that represent the optical device business, which SEDI develops and manufactures, are laser diodes and light-receiving elements used for optical fiber communications. As the volume of data traffic is continuing to explode today, laser diodes, which convert electrical signals into optical signals, are installed in optical communications systems for data centers and in optical fiber communications networks that connect mobile phone base stations.

With data transmission capacity and speed continuing to increase, we have been working on the development of devices in line with that trend from early on. While ensuring close communication with customers, we proceed with our product development in parallel with the customers’ development. We have introduced concurrent engineering to shorten the development period and improve our efficiency.

To what extent can we realize new functions and performance with new materials?

SEDI is a technology development-oriented organization in which many of the employees are engineers. We always discuss what to do to achieve new functions and performance using new materials. The Sumitomo Electric Group’s Transmission Devices R&D Laboratory develops advanced technology, while SEDI develops products using technology developed by the laboratory. While ensuring cooperation between the two organizations, we have released competitive products to the world.

HEMT, which is the basis of GaN HEMT and pivotal in the evolution of the world’s info-communications technology, is a technology that originated in Japan. We have handled this material for more than 40 years. We have abundant know-how and technology that enables stable mass production ahead of other companies.

SEDI is the only device manufacturer in the world that develops and manufactures both electronic and optical devices. This is partly due to the company’s history starting from the integration and reorganization of the former Fujitsu Quantum Device, Ltd. and Sumitomo Electric’s operations in the fields of electronic and optical transmission devices.

Although the same compound semiconductor material is used, there are differences between electronic devices and optical devices in terms of product properties and their respective engineers’ perspectives. By taking advantage of these differences, we are focusing on the development of common in-house manufacturing technologies and production systems, and striving to demonstrate synergy.

New perspectives gained through two assignments - wafer process and design

I feel the power of synergy through my own experience. As a wafer process engineer, I worked in a clean room, a relatively closed world, for a while after I joined the company.

In the same office there was a design team, which had a point of contact with the outside world. Seeing the design team engaging in business talks with customers from other countries, I wanted to work in the outside world. “I want to be out there too,” I thought. So I consulted my boss, who said that I should first build my career in the field of design, and I began to work in design in Japan.

It was in my ninth year after entering the company when I was finally assigned to work in North America. As an engineer for customers, I introduced products and provided technical support. About once a month, I traveled through the U.S. together with a local sales representative for a week. Most of my work involved dealing with problems, meaning that I needed to continue conceiving solutions every day under great pressure. This made me realize there was a lot more to working overseas than I had thought.

After spending four years in North America, I returned to Japan. I was thinking about going back to the field of wafer processing rather than design. This was because during the four years, I had conceived a wide variety of ideas, including ideas related to process technology. In the end, I returned to product development as a designer, but the process perspectives and design experience that I had gained in North America combined and served as a driving force for generating new ideas.

How to clear up social contradictions. I want to contribute to the solution.

My four years in North America served as a good opportunity to review my work in Japan objectively. This gave me insights that I could apply to my next attempt, such as “I should have done this at that time” or “that was the problem” or “it looks like this will happen in the future.” I think that by keeping a physical distance from Japan, I was able to foster my abilities to see things from both a “bird’s eye” and “insect’s eye” view. Since then, the way I work has changed.

Engineers tend to be absorbed in the world of the microscope, but they need to step slightly back from there and see society and the future from a wider perspective.

What we look ahead to now is the solution of social contradictions arising along the path to carbon neutrality. Many countries and regions are trying to control CO2 emissions toward achieving carbon neutrality, while data traffic is expected to continue to increase in the future, with power consumption at data centers and mobile phone base stations continuing to increase at breakneck speed.

How should this contradiction be cleared up? Our compound semiconductor devices can contribute to solving challenges generated in an advanced information society. To provide communication semiconductor devices that realize larger data communications and lower power consumption than any other devices—this is our mission. We are taking on the challenge of fulfilling this mission with an “insect’s eye” for pursuing technology and a “bird’s eye” for looking at the future.

Yuichi Hasegawa
Yuichi Hasegawa


Yuichi Hasegawa

Joined Fujitsu Ltd.

Sumitomo Electric Device Innovations, Inc. is established.

General Manager, Transmission Devices Division
President, Sumitomo Electric Device Innovations, Inc.

Executive Officer
General Manager, Transmission Devices Division
President, Sumitomo Electric Device Innovations, Inc.

SNS share