Nd: YAG is a solid state laser four level laser. Nd stands for neodymium and YAG for Yttrium aluminium garnet (Y₃Al₅O₁₂). It is developed by J.E. Geusic, H.M. Marcos and L.G. Van Vitert in 1964. The rod of Y₃Al₅O_12­ is doped 1% with triply ionized neodymium. Nd³⁺ ions will replace the Y³⁺ ions in the crystal. Maximum length of the rod is about 10 cm and diameter is 6-9 cm.

Active medium: Nd³⁺ ions act as active medium or active centers. YAG is just the host.

Pumping source: The pumping of Nd³⁺ ions to upper levels is done by krypton arc lamp. Xenon lamp can also be used as pumping source. Thus, the optical pumping is used to achieve population inversion.

Optical resonator system: The ends of the Nd:YAG rod are polished and silvered so as to act as the optical resonator system.

Note: In next article, I will explain the working. Till then, try to make the construction diagram. In case of any problem, post in the comment section.

Reference: This article is referred from my authored book “optics and lasers” having ISBN 978-81-272-2948-2

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