researchers are accelerating the exploration of novel optical materials suitable for photonic integrated circuits and smart contact lenses, and molybdenum oxychloride (moocl₂) crystals have emerged as one of the most promising candidates, thanks to their unique and largely unexplored optoelectronic properties.
this crystal exhibits an unprecedented anisotropic optical response: along certain crystallographic axes, it displays metallic‑like high reflectivity, while in the perpendicular direction it demonstrates glass‑like high transmittance. even more remarkable is that it achieves the strongest birefringence ever observed among natural materials, enabling ultra‑thin optical components based on this material to be compressed to a thickness comparable to one thousandth of the diameter of a human hair.
critically, the research team has, for the first time, observed a pronounced slow‑light effect and localized electromagnetic field enhancement in moocl₂ at 512 nanometers (in the green light range). under these resonant conditions, the speed of light propagation is significantly reduced, while the electric field intensity is amplified by several orders of magnitude. owing to its exceptional light‑confinement capabilities, this crystal can efficiently guide optical signals through subwavelength‑scale nanochannels with virtually no scattering losses, providing a completely new physical platform for developing highly integrated polarization modulators, low‑loss on‑chip waveguides, and high‑performance nonlinear nanophotonic devices.
