Optics 101

Nd:YAG Lasers – Properties and Applications

Neodymium-doped yttrium aluminum garnet (Nd:YAG) is a crystal that is commonly used as a lasing medium for solid-state lasers. J. E. Geusic et al first explained the laser operation of Nd:YAG at Bell Laboratories in 1964. Nd:YAG is formed by replacing a small quantity of yttrium ions in the YAG crystal structure with triply ionized neodymium that serves as a dopant. The ions are replaced due to the fact that they are of same size. The neodymium ion acts as the lasing medium in the Nd:YAG crystal.

Nd:YAG laser consists of a four-level gain medium that offers extraordinary laser gain at moderate pump intensities and excitation levels. The gain bandwidth of the laser is relatively small, which in turn improves laser’s gain efficiency thereby minimizing threshold pump power. It emits infrared light in the range of 1064 nm. It can be lamp pumped or diode pumped. Lamp pumping can be achieved because of the four-level characteristics and broadband pump absorption of the laser in the 800 nm band region.

Nd:YAG is commonly used in its monocrystalline form, which is manufactured using the Czochralski growth method. However, large ceramic Nd:YAG of high quality are also being widely developed.

Laser Properties

Laser Properties
Laser type Solid
Pump source Laser
Operating Wavelengths
1064 nm
940 nm
1120 nm
1320 nm
1440 nm

Physical and Chemical Properties

Physical and Chemical Properties
Chemical formula Nd:Y3Al5O12
Molecular weight 595.3 g/mol
Crystal structure Cubic
Melting point 1970°C
Mohs hardness 8.5
Thermal conductivity (@20°C) 14 W/mK
Specific heat capacity 0.59 Jg-1K-1
Young's modulus 280 GPa

Applications

Nd:YAG laser can be used in manufacturing for engraving and etching various metals and plastics, and for cutting and welding semiconductors, steel and other alloys. It is also employed for making subsurface markings in transparent materials such as acrylic glass or glass. It produces continuous laser at room temperature, and can be used as a portable system as the rods are small.

Some of the other common applications of Nd:YAG laser include the following:

  • It is used in ophthalmology to correct posterior capsular opacification, and oncology to treat benign thyroid nodules, primary and secondary malignant liver lesions and skin cancer.
  • It can also be used for flow visualization techniques in fluid dynamics
  • It is the most common laser used in laser rangefinders and laser designators
  • It is used as pumping tunable visible light lasers
  • It is used for research applications such as mass spectrometry, remote sensing and Raman spectroscopy.

References

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