population inversion
Excited majority state
Population inversion is a condition in physics where more atoms or molecules occupy a higher energy state than a lower one—the reverse of normal thermal equilibrium.
This unstable arrangement is essential for laser operation: when achieved, stimulated emission can dominate over absorption, allowing light amplification.
The ruby rod reaches population inversion when pumped with sufficient energy.
Concentrated light device
- maserMicrowave frequency amplifier
- coherent lightIn-phase electromagnetic radiation
- photonicsLight particle science and engineering
- spectroscopyStudy of light-matter interaction
Stimulation of response
- energy transferPower moving between systems
- absorptionProcess of taking in
- emissionDischarged substance or act
- cascade effectSequential chain of consequences
feedback mechanism · saturation · amplification · relaxation
Elevated energy configuration
- ground stateLowest possible energy configuration
- upper levelHigher story of building
- energy levelsGradations of physical vitality
- quantum statesProbabilistic particle descriptions
thermal equilibrium · lifetime · decay rate · spontaneous emission · degeneracy · sublevel
laser
Concentrated light device
- maserMicrowave frequency amplifier
- coherent lightIn-phase electromagnetic radiation
- photonicsLight particle science and engineering
excitation
Stimulation of response
- energy transferPower moving between systems
- absorptionProcess of taking in
- emissionDischarged substance or act
cascade effect · feedback mechanism · saturation · amplification · relaxation
excited state
Elevated energy configuration
- ground stateLowest possible energy configuration
- upper levelHigher story of building
- energy levelsGradations of physical vitality
quantum states · thermal equilibrium · lifetime · decay rate · spontaneous emission · degeneracy · sublevel
- inversionsflip, handstand, reversal, upside down, upside-down
- quantum transitionsquantum jump, quantum leap, excited state, ground state, energy levels
population inversionthermal equilibrium
Equal temperature throughout system
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