Synthetic single-crystal sapphire (Al2O3) is the leading material for highly advanced optical applications due to a unique combination of excellent optical, physical and chemical properties. It is transparent over a wide range of wavelengths from vacuum ultraviolet to infrared regions (from 0.18 µm to 6 µm). Due to its hexagonal crystalline structure, sapphire shows anisotropic behaviour in its optical and physical properties. Therefore the exact characteristics of optical components made from sapphire depend on the crystallographic direction relative to the optical axis (C-axis, 0001). Sapphire possesses birefringence on all directions except for the c-axis. Sapphire is the hardest among all oxide crystals. Due to its extreme surface hardness, sapphire can be scratched by only a few substances (for example, diamond and boron nitride). It's great strength allows for the production of much thinner optical windows compared to other materials. Yet another reason to employ sapphire at wavelengths close to the transmission limit.
We can deliver the Sapphire material produced by two different methods of sapphire growth:
Kyropoulos method: is used to produce a large boule of sapphire, typically of a cylindrical form. Grown boule can be from 70 up to 300 mm in diameter and up to 250 mm in height. Sapphire grown by this method normally has a very high optical quality with low defect density with efficient costs, and can be cut into wafers of any crystallographic orientation. This method is applied for manufacturing substrates for blue LEDs and SOS wafers.
Stepanov method (EFG): a shaped growth technique used for growing sapphire in near-net finished shape, including tubes, rods, sheets, and fibers. This technique can also provide unique shapes and sealed assemblies. By Stepanov method, ribbon crystals up to 500 mm long and 80 mm wide are grown. Crystals grown by this method can have different crystallographic orientations (A, R, random) and are mainly used for industrial & mechanical applications, where good optical qualities are not important.