Lasers
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See all →- What is population inversion and why is it necessary for laser action? In one line Population inversion is the state in which more atoms are in a higher energy level than in a lower one, and it is needed so that... 1
- What is pumping in a laser and what are the different methods of pumping? In one line Pumping is the process of supplying energy to the active medium to lift atoms to higher energy levels and create population inve... 1
- What do active medium and active centre mean in a laser? In one line The active medium is the material in which population inversion and light amplification take place, and the active centres are t... 1
- What is the difference between spontaneous emission and stimulated emission of radiation? In one line In spontaneous emission an excited atom drops to a lower level on its own and emits a photon in a random direction and phase, wh... 1
- What is the resonant (optical) cavity in a laser and what job does it do? In one line The resonant cavity is a pair of mirrors around the active medium that sends light back and forth through it many times, buildin... 1
- What are coherence length and coherence time, and how are they related? In one line Coherence time is the time for which a light wave keeps a fixed, predictable phase, and coherence length is the distance the wav... 1