Democratization of Integrated Photonics

Silicon semiconductors, when processed to be as thin as a few hundredths of a human hair, are known to function as optical waveguides that can guide light (photons) freely and with high efficiency. By leveraging the advanced microfabrication technologies developed in the semiconductor industry, it is possible to create integrated photonics circuits with silicon nanowires intricately wired in extremely small spaces. This technology, known as silicon photonics, has already been commercialized and is regarded as an essential element for realizing next-generation AI, quantum technologies, and optoelectronic integration.

In the latest research on integrated photonics, a central theme is the integration of silicon with heterogeneous materials such as compound semiconductors. Because this involves docking non-conventional materials onto silicon, it requires advanced, specialized (and expensive) microfabrication equipment. This aspect of research into heterogeneous material integration for photonics means that it is often accessible only to well-funded research groups. During a night session at an international conference I happened to attend in the United States, I learned that many researchers are dissatisfied with this situation.

The transfer printing method I am researching is a pick-and-place integration technique that uses viscoelastic rubber, enabling advanced research on heterogeneous material integration for photonics without a large financial investment. At the aforementioned night session, an audience member pointed out that this low-cost transfer printing method could enable the "democratization of integrated photonics research." I was impressed by this interesting perspective, one that is not often discussed in Japan. For a specific research field to develop significantly, the number and diversity of its participants are crucial. I found it fascinating to consider focusing on the democratic nature of technology to ensure the continued expansion of my own research field.

The ultimate integrated photonics structure I envision (as illustrated in Figure 1) is one where optical elements with special functions, made from a wide variety of materials, are freely combined on a silicon photonics optical circuit. The idea is that unconventional combinations will give rise to new functions and superior performance. I imagine it will become an indispensable device for applications that demand extreme performance, such as quantum technologies. This could also be described as a technology that cannot be realized without forming teams with experts in each material and advancing the research in a somewhat democratic manner. However, I believe it is important to decide the direction of one's own research independently.