Formation of photonic structures in glasses through phase separation

Uniformly size-distributed lithium-niobate microspheres were formed in a vitreous matrix through a liquid–liquid phase separation of glass under heat treatment. The size of the crystallites varied from 4 to 90 μm depending on the temperature and the duration of the anneal. The structures were studied by optical diffraction, microscopy as well as by Raman and X-ray techniques.