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A joint research team from Chiba University and Tohoku University has successfully demonstrated a new method using terahertz light to visualise the two-dimensional spatial distribution of right- and left-handed chirality across an engineered metasurface, overcoming long-standing limitations in materials science and biology
Chirality refers to structural configurations that exist as non-superimposable mirror images of one another, a concept frequently likened to human hands. This structurally asymmetrical geometry is a fundamental property of nature.
It dictates the behaviour of vital biological mechanisms, such as the twisting structure of DNA, and plays a crucial role in drug discovery, advanced nanotechnology, and materials science.
A traditional technique for evaluating the structural handedness of a sample involves measuring its optical response to circularly polarised light. This is particularly effective within the terahertz (THz) spectrum—an electromagnetic band situated between microwaves and infrared light that is highly responsive to the subtle collective vibrations and twisting formations of complex molecules.
However, conventional terahertz spectroscopy has suffered from a significant diagnostic constraint: it averages the optical data across the entire sample area. This makes it impossible to map out exactly how chirality varies across different points on a single surface.
Engineering a chiral map via moiré metasurfaces
To overcome this spatial limitation, a collaborative research group led by Professor Katsuhiko Miyamoto and first author Uina Chiba from Chiba University, alongside Dr Seigo Ohno of Tohoku University and Dr Takeo Minari of the National Institute for Materials Science, developed a customised testing landscape.
The team engineered a moiré-type metasurface by overlapping microscopic, micrometre-scale silver disk patterns with a slight angular rotation. This geometric fabrication allowed them to deliberately arrange distinct right-handed and left-handed twisting configurations right next to each other on a single, uniform sheet.
When the researchers targeted this manufactured surface with circularly polarised terahertz waves, different regions demonstrated vastly opposing spectral responses based on their local orientation. Published in the journal ACS Photonics on June 2, 2026, the study verified that the system could resolve distinct areas of alternating structural handedness at a spatial resolution of roughly 100 micrometres (μm), dimensions comparable to the thickness of a single human hair.
Future industrial and diagnostic applications
By directly visualising the coexistence of opposing spatial chirality for the first time, this imaging framework offers a non-destructive verification method for the manufacturing of advanced nanomaterials. Looking forward, the research team aims to broaden the scanning frequency range to span 2 to 15 THz.
This expansion will enable deeper structural analyses, potentially paving the way for non-invasive medical diagnostic systems capable of mapping abnormal protein aggregates linked to diseases. Furthermore, the technology shows immense promise for inspecting next-generation signal-control devices in Beyond 5G and 6G communication networks, as well as detecting micro-distortions buried inside soft materials and quantum systems.