Sapphire is a single crystal aluminum oxide (Al2O3). It is one of the hardest materials. Sapphire has good transmission characteristics over the visible, and near IR spectrum. It exhibits high mechanical strength, chemical resistance, thermal conductivity and thermal stability. It is often used as crystal materials in specific field such as space technology where scratch or high temperature resistance is required

1. Synthetic Sapphire, the single crystal form of Al2O3, is one of the hardest materials ( 9 Mohs hardness). Because of its structural strength, the sapphire crystal can be made much thinner than other common optical crystals, with better transmittance performance.

2. High thermal stability and excellent thermal conductivity make the sapphire crystal suitable for the applications in high power. The loss in a sapphire crystal is less than in another common optical crystal.