Research

Meta-Optics & Nanophotonics: Light Physics with Artificial Structures

Recent advances in micro- and nanofabrication have enabled the creation of structures on the scale of the wavelength of light (hundreds of nanometers). By engineering such subwavelength structures, meta-optics and nanophotonics aim to control light in unprecedented ways. Our research focuses in particular on photonic crystals and metamaterials/metasurfaces—platforms that have been developed by incorporating ideas from condensed-matter (solid-state) physics. These studies are expected not only to enhance the performance and functionality of optical components such as lenses and mirrors, but also to contribute to emerging technologies including optical communications and optical computing. In our group, we explore new light physics and photonic functionalities using artificially structured metasurfaces and photonic crystals.

Topological Photonics

Topological photonics is a field of nanophotonics that leverages concepts from topology. Topology—often described as “soft geometry”—is a branch of mathematics that focuses on global features of shapes rather than detailed geometry. A classic illustration is the equivalence between a doughnut and a mug: because one can be continuously deformed into the other, topology regards them as the “same.” It has been discovered that such seemingly counterintuitive ideas can help us understand real materials and their properties; one prominent example is the topological insulator. Topological insulators exhibit fascinating behavior, such as conducting electricity on their surface while remaining insulating in the bulk. These topological concepts can also be applied to nanophotonic systems, where analogous phenomena are expected to emerge—potentially enabling new optical functionalities.

Non-Hermitian Photonics

Traditional condensed-matter (solid-state) physics has mainly focused on energy-conserving systems described by Hermitian operators. In contrast, there has been growing interest in non-energy-conserving “non-Hermitian” systems, which can exhibit phenomena absent in Hermitian settings. Nanophotonic structures are inherently non-Hermitian due to radiation and other loss channels, and therefore provide a natural platform for realizing non-Hermitian physics. In addition, the distinctive effects enabled by non-Hermitian systems in nanophotonics (for example, different responses depending on whether light is incident from the left or the right) can be readily translated into practical photonic functionalities, driving active research in this area.

Optical Physics in Aperiodic and Quasiperiodic Systems

Many studies in nanophotonics use periodic structures, in part because they are easier to design, fabricate, and analyze, and periodic systems have been extensively explored across science. Meanwhile, aperiodic systems—represented by quasicrystals, which were recognized by the 2011 Nobel Prize in Chemistry—can exhibit intriguing properties distinct from those of periodic systems. We aim to explore such properties in nanophotonic platforms and to translate them into novel photonic functionalities.

Research Topics

Coming soon...