Nd:YAG (Neodymium-doped Yttrium Aluminum Garnet) is a crystal material used as an active medium in laser systems. It is made by doping a crystal of yttrium aluminum garnet (YAG) with neodymium ions, which provide the laser with the energy necessary to produce laser light. The crystal has a strong transparency in the range of 400 nm to 2600 nm and has high thermal and optical damage resistance, making it ideal for use in high-power laser systems. Additionally, Nd:YAG has a large gain bandwidth, making it suitable for generating laser pulses with short durations. It is one of the most widely used laser crystals due to its robustness, high efficiency, and versatility in a wide range of laser applications, including medical, industrial, and scientific applications.