Harvard Unveils Device to Actively Control Light Chirality

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Researchers at Harvard's John A. Paulson School of Engineering and Applied Sciences have developed a groundbreaking device that can actively control the 'handedness' or chirality of light. This compact chip, built using twisted bilayer photonic crystals and a micro-electromechanical system (MEMS), promises to reshape fields ranging from medical diagnostics to high-speed data transmission.

Why it matters

The ability to precisely manipulate light chirality has far-reaching implications. In chemistry and medicine, molecules with identical chemical formulas but different spatial arrangements (mirror images) can have drastically different effects. This device overcomes limitations of current tools, offering a dynamic and adaptable platform for chiral analysis with applications in areas like sensing, optical communication, and quantum photonics.

The details

The device works by introducing asymmetry into the photonic crystal structure through the stacking and rotation of two silicon nitride layers. This 'twisting' of the layers allows for precise control over the chirality of light, adjusting its response to different types of chiral light in real-time without needing component replacement. The MEMS system enables dynamic tuning of the twist angle and layer spacing to achieve near-perfect selectivity between left- and right-circularly polarized light.

• The research was published in Optica on March 22, 2026.

What’s next

Researchers are exploring ways to integrate this technology into more complex photonic circuits and systems, including the development of integrated photonic chips and the use of metamaterials and artificial intelligence in optical design and optimization.