Neodymium doped Yttrium Aluminum Garnet (Nd:YAG) is the most commonly
employed solid state lasing medium for material processing applications. Nd:YAG has relatively good optical absorption and conversion efficiency, low lasing threshold and good thermal dissipation for high power operation.

Unmounted Rods

Nd:YAG laser optically pumped by Xenon or Krypton lamp

Neodymium (Nd) is the active laser medium in an Nd:YAG laser system. It is an excellent laser medium because it responds well to optical pumping and reaches laser threshold relatively easily. Its threshold is low because it achieves population inversion via a 4-level pumping scheme (see illustration below).

If light from a Xenon or Krypton lamp is reflected into the Nd:YAG rod, some of it will be of the proper energy and wavelength to be absorbed by the Nd atoms, exciting some electrons from the ground state (EO) to the highest energy level (E3). This is called optical pumping.

Mounted rods

For efficient optical coupling, the rod and pump-lamp are usually positioned close to each other inside a reflective housing. For low power applications, such as marking or resistor trimming, the rod can be continuously pumped by an arclamp; for higher power applications, such as drilling or welding, the rod is usually pumped by repetitive pulses from a flashlamp. However, some continuously pumped high power systems have recently been developed.

Other Host Materials
In addition to YAG, Neodymium can be doped into glass. Glass has a few advantages over YAG: it is non-crystalline which makes it less expensive and crystalline strain issues do not apply so higher dopant levels can be achieved. Therefore, Nd: Glass rods can very efficiently produce high energy pulses. The main disadvantage to glass is its comparatively low heat dissipation capabilities. So, while Nd:Glass rods can produce high energy pulses, repetition rates must be kept low to keep the average power level down. This limits Nd: Glass to low frequency applications such as spot welding or drilling.

*For more detailed information about rod pumping and manufacturing, please see our catalog pages 119-122. (click here to view the catalog , *.pdf)