ifos • paper_1 • waves_oscillationsifos-2018-subject-02-006
[UPSC IFoS 2018] Polarisation and Modern Optics (Q357, 8+7=15M)
(i) What is population inversion? How is it efficiently achieved in He-Ne laser? Show it with necessary energy levels diagram.
(ii) Show that for a normal optical source emitting at 600\text{ nm} at a temperature of 10^3\text{ K}, the spontaneous emission dominates over stimulated emission.
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