Two decades of progress for photonic crystals: from the realization of complete 3D crystals to the state of the art for society 5.0

Abstract

Almost two decades have passed since the realization of complete 3D photonic crystals at optical wavelengths. During these years, the manipulation of photons by photonic crystals has progressed tremendously. For example, the concept of confining photons to a very small modal volume has been established and nanocavity Q-factors have exceeded ten million, enabling platforms for strong light-matter interaction and quantum information processing. Photonic crystals allow even a broad-area manipulation of photons, by which semiconductor lasers with a very bright, narrow-divergence beam and various functionalities including 2D beam steering have been realized. Such lasers are promising for applications in light-detection and ranging (LiDAR) and direct material processing, which are important for the forthcoming Society 5.0. Photonic crystals also enable thermal emission control, by which the issues of conventional thermal emission devices such as their extremely broad emission spectra and slow response speed have been fixed, and a renovation of thermal emission devices has been achieved. In this plenary talk, we will review such progress of photonic crystals including their social applications.