Kiichi Hamamoto

Kiichi Hamamoto

Kyushu University, Japan

For pioneering contributions to opto-electronic devices, photonic integration circuit technologies for optical communications and sensing, their fabrication technologies including crystal growth and dry-etching, and contributions to academic societies

Kiichi Hamamoto remembers starting to think with a scientific approach at the age of 6. His father had purchased a plastic model car and Kiichi needed to assemble an electric circuit to power it. At this time, he did not understand the principle behind electric power, but knew that he had to be careful not to mix up the positive and negative wires, or the circuit would not work. After several attempts, he found the right combination and the car worked. Since then, he has been interested in the mechanisms and reasons behind the way things worked. In high school, he realized he needed to study concepts at a deeper level in order to truly understand the “why” and the “how.” It was at this moment that he first decided on his career path.

When he started researching on photonic integrated circuit design at NEC Corporation in the late 1980s, a supervisor explained to him that waveguide width must be designed with single-mode condition. The supervisor told him that was common knowledge and the accepted theory. However, Kiichi felt this limited approach was odd and potentially incorrect.  

He developed an idea to use multi-mode interference to overcome the constraints of the single-mode condition. He took this idea and considered applying it to active devices, like laser-diodes. At this time, he was an academic guest at ETH Zurich in Switzerland and was allowed latitude in his research topic, so he decided to pursue his idea. Many people doubted him and even recommended that he change direction, but Kiichi persisted and ended up completing his Ph.D. on this topic at ETH Zurich in 2000.

Kiichi says that he would not have been able to complete this work without the help of his mentor, Professor Hans Melchior, at ETH. Professor Melchior was well-known in the field, accepted Kiichi into his lab, and allowed him to proceed with the device implementation and trial that ultimately led to his doctorate.

Today, Kiichi is Professor of Electrical Engineering Sciences at Kyushu University in Japan where he leads the Opto-Electronics Laboratory. They still exploit the laser configuration that Kiichi discovered at ETH to direct modulation of the laser diode. At OFC 2018, Kiichi and his team presented high-speed modulation on individual different space modes. In addition, Kiichi and his team are researching breath-sensing devices which they hope will be integrated into mobile phones to give people an easy way to check their health at any time and any place. Kiichi says that this research was inspired by an Optics & Photonics News article about breath-sensing using infrared absorption. Without this, he would have never started the research.

“If you believe your idea works well, then you should do it,” Kiichi says. “Trust yourself.”

Profile Written by Jeanette Gass