Materials built from one-dimensional chains or tubes respond to light differently depending on its direction, which is useful for polarisation-sensitive devices. An international team has synthesised a new form of elemental phosphorus: a direct-bandgap semiconducting single crystal made of wavy polygonal tubes.

X-ray diffraction and transmission electron microscopy revealed its monoclinic structure. The crystal shows giant birefringence in visible and near-infrared light, together with strongly orientation-dependent photoluminescence, Raman scattering and second-harmonic generation. The authors say this opens avenues for on-chip polarisation devices and nonlinear photonic circuits. From QMAT, Zhipei Sun of Aalto University's Photonics group is a co-author; the large team spans institutions in China, Hong Kong and the UK.

Figure: Zhang et al., Nat. Commun. (2026), CC BY 4.0