NGG (Nd3Ga5O12) is a rare earth gallium garnet (REGG) material, which is a crystal structure composed of neodymium, gallium, and oxygen atoms. It is used as a substrate material in various applications such as electro-optical devices, laser components, and infrared windows.
One of the main advantages of NGG substrates is that they have a high thermal conductivity, which makes them suitable for use in high-power and high-temperature applications. Additionally, they have a high mechanical hardness, making them resistant to damage from thermal and mechanical stresses. They also have a high refractive index, which makes them useful for optical applications.
NGG substrates are typically produced through a growth process called crystal pulling, in which a seed crystal is slowly pulled from a melt of the desired material. This allows for precise control over the crystal structure and reduces defects in the material.