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Engineering Physics by S. Mani Naidu

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10.3 Spontaneous and stimulated emission

In lasers, the interaction between matter and light is of three different types. They are: absorption, spontaneous emission and stimulated emission. In these processes, two energy levels of atoms are involved. As shown in Fig. 10.1, Let E1 and E2 be ground and excited states of an atom. The dot in Fig. 10.1, represents an atom. Transition between these states involves absorption or emission of a photon of energy E2E1 = 12, where ‘h’ is Planck’s constant. Now, we study these processes in detail.

 

Figure 10.1 (a) Absorption; (b) Spontaneous emission; (c) Stimulated emission

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(a) Absorption: As shown ...

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