Terahertz Imaging Reveals Chirality Across a Surface
A breakthrough in spatial mapping could impact everything from biomolecular analysis to 6G device inspection.
Scientists at Chiba University and Tohoku University have developed a technique using terahertz imaging to map the spatial distribution of left- and right-handed chirality across a material's surface. The method was demonstrated on a moiré-type metasurface, achieving a resolution of approximately 100 micrometers—comparable to the thickness of a human hair.
The research team fabricated the metasurface by stacking microscopic patterns of silver disks with slight offsets or rotations, creating regions with different chirality. Using circularly polarized terahertz waves with a spiral-shaped profile, the researchers spatially resolved the distribution of chirality.
The study, published in ACS Photonics on June 2, 2026, represents the first direct observation of spatial chirality distributions within a material. Potential applications include quality evaluation of chiral materials, biomolecular structure analysis, diagnosis of abnormal protein aggregates, inspection of 6G communication devices, and development of terahertz devices. The authors suggest the technique could be extended to the 2–15 THz range for more detailed structural analysis.
A Compact Device Actively Controls Light's Handedness
This tunable system offers full control over optical chirality, enabling selective detection of mirror-image molecules.
Researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have developed a compact device capable of actively controlling optical chirality. The project was led by graduate student Fan Du and Professor Eric Mazur, with co-authors including Haoning Tang, Yifan Liu, Mingjie Zhang, Beicheng Lou, Guangqi Gao, Xuyang Li, Alsyl Enriquez, and Shanhui Fan.
The device uses a reconfigurable twisted bilayer photonic crystal—two layers of patterned silicon nitride that can be precisely rotated relative to each other. An integrated micro-electromechanical system (MEMS) controls both the twist angle and the spacing between the layers in real time. When the layers are brought together and rotated, the structure creates geometrical chirality, resulting in different transmission behaviors for left- and right-circularly polarized light.
The study, published in Optica, demonstrates that this approach offers full tunability, allowing the device's response to different types of chiral light to be continuously adjusted without replacing components. The MEMS system enables the device to achieve near-perfect selectivity in distinguishing the handedness of light.
Chirality is significant in fields including pharmaceuticals, chemistry, and biology. For example, mirror-image molecules can exhibit different biological effects, as seen with the drug thalidomide, where one chiral form had therapeutic effects while its mirror image caused birth defects. Scientists use chiral light to study such molecules, but traditional tools have fixed capabilities and limited operating ranges.
The Harvard device addresses this limitation by offering tunable detection across different wavelengths. Potential future applications include chiral sensing, where the device could be tuned to detect specific molecules, and dynamic light modulation in optical communication systems, enabling precise control of light on a chip. The study also outlines a broader design strategy for creating twisted bilayer photonic crystals with controllable optical chirality.