In the last article, I have explained the construction of Nd:YAG laser. Today, I will explain the working of it:

Nd:YAG is a four level laser system. The pumping of neodynium (Nd3+) ions to upper state (E4) is done using krypton arc lamp. Thus optical pumping is used in this laser. The wavelength of light of wavelength 7200 Å to 8000 Å excites the ground state (E1) Nd3+ ions to E4 states. From E4 states, they make a non-radiative transition and come to E3 state. E3 is the metastable state so population inversion is achieved between the levels E3 and E2.

After this, the process of stimulated emission will occur. (I have already explained the process of stimulated emission in detail in my previous articles).Thus, the laser emission will occur in between the levels E3 and E2 with the process of stimulated emission. So E3 is the upper laser level and E2 is the lower laser level. Then Nd3+ ions come back to the ground state E1. Laser emission will have wavelength  of 10600 Å so occur in the infrared range of spectrum.

Note: In next article, I will explain about the output and major applications of Nd:YAG of this laser. Till then, try to make the working 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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