Light can exhibit right- or left-circular polarization. How this so-called optical chirality can be deliberately controlled is now demonstrated by a research team from the Leibniz Institute of Photonic Technology (Leibniz-IPHT) and Ludwig Maximilian University of Munich.

The researchers, first author Wenqin Huang and the team led by Prof. Markus Schmidt, head of the Fiber Photonics research department and professor at the University of Jena, fabricated hollow-core “light cages.” These cage-like waveguides consist of multiple spirally arranged strands that guide light within the central hollow core. By intentionally twisting the structure, the polarization degeneracy of the guided modes is lifted, causing right- and left-circularly polarized light to propagate differently.

Using the Jones formalism, the team systematically analyzed how the structures modify polarization. The results reveal how linear and circular birefringence, together with dichroism, interact to determine the resulting polarization state.

To reliably fabricate the delicate cages, the researchers also developed a tailored, code-based writing strategy for nanoprinting. This approach avoids typical raster artifacts associated with STL import and yields more homogeneous structures. At the same time, the team identified practical limits: at very high twist rates, the geometric fidelity of the printed strands decreases because the structure becomes increasingly dominated by the shape of the printing voxel.

In the long term, such tailored microstructures could serve as compact polarization components—for example in integrated photonics, fiber-based sensing systems, or the analysis of chiral molecules.

Publication: Wenqin Huang, Johannes Bürger, Jun Sun, and Markus A. Schmidt, “Distinct geometry-induced optical chirality in vertically nanoprinted hollow-core light cages”, Optica 13, 303-312 (2026), https://opg.optica.org/optica/fulltext.cfm?uri=optica-13-2-303